Apparatus and method for pulsed-mode charge detection mass spectrometry

Abstract

The charge detection mass analyzer includes an ion trap configured to receive and store ions and selectively release stored ions therefrom, and an electrostatic linear ion trap (ELIT) remote from the ion trap, the ELIT including first and second ion mirrors and a charge detection cylinder disposed therebetween, means for selectively controlling the ion trap to release at least some of the stored ions and cause them to move into the ELIT, and means for controlling the first and second ion mirrors to trap one of the ions passing therethrough in the ELIT and oscillate the trapped ion back and forth between the first and second ion mirrors, each time passing through the charge detection cylinder and inducing a corresponding charge.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 62 / 905921, filed September 25, 2019, the disclosure of which is expressly incorporated herein by reference in its entirety.

[0002] Government Rights

[0002] This invention was made with Government support under GM131100 awarded by the National Institutes of Health.

[0003] FIELD OF THEINVENTION This invention relates generally to charge detection mass spectrometry instruments, and more particularly to apparatus and methods for pulsed mode operation of such instruments. [Background technology]

[0004]

[0004] Mass spectrometry provides identification of chemical components of a substance by separating gaseous ions of the substance according to the mass and charge of the ions. Various instruments and techniques have been developed for determining the mass of such separated ions, and one such technique is known as charge-detection mass spectrometry (CDMS). In CDMS, the mass of an ion is determined as a function of a measured ion mass-to-charge ratio, typically referred to as "m / z," and the measured charge of the ion.

[0005]

[0005] The high level of uncertainty in the m / z and charge measurements of early CDMS detectors led to the development of electrostatic linear ion trap (ELIT) detectors, in which ions are made to oscillate back and forth through a charge detection cylinder. Multiple passes of ions through such a charge detection cylinder provide multiple measurements for each ion, with the uncertainty in the charge measurement being n 1 / 2 where n is the number of charge measurements. However, such multiple charge measurements necessarily limit the rate at which ion m / z and charge measurements can be obtained using current ELIT designs. It is therefore desirable to seek improvements in ELIT design and / or operation that increase the rate of ion m / z and charge measurements beyond those obtainable using current ELIT designs. Summary of the Invention

[0006]

[0006] The present invention may include one or more of the features recited in the appended claims and / or one or more of the following features and combinations thereof: In one configuration, a charge detection mass analyzer includes an ion source configured to generate ions from a sample, an ion trap configured to receive and store the generated ions therein and to selectively release the stored ions therefrom, an electrostatic linear ion trap (ELIT) remote from the ion trap and including first and second ion mirrors and a charge detection cylinder disposed therebetween, and means for selectively controlling the ion trap to release and move at least some of the ions stored therein towards the ELIT and for controlling the first and second ion mirrors to trap at least one ion of the ions passing therethrough in the ELIT and to oscillate the at least one trapped ion back and forth between the first and second ion mirrors, each time passing through the charge detection cylinder and inducing a corresponding charge therein.

[0007]

[0007] In another configuration, a charge detection mass analyzer includes an ion source configured to generate ions from a sample, at least one voltage source configured to generate a plurality of output voltages, an ion trap coupled to a first set of the plurality of output voltages, the ion trap configured to receive and store generated ions therein in response to a trapping state thereof, and to selectively release stored ions therefrom in response to a transmission state thereof, and an electrostatic linear ion trap (ELIT) spaced from the ion trap, the electrostatic linear ion trap including a front ion mirror and a rear ion mirror and a charge detection cylinder disposed therebetween, the front ion mirror and the rear ion mirror being coupled to a second set of the plurality of output voltages and a third set of the plurality of output voltages, respectively. an electrostatic linear ion trap configured to transmit ions therethrough in response to its transmission state and to reflect ions entering therein from the charge detection cylinder back to the charge detection cylinder in response to its reflection state; and processing circuitry for controlling a first set of voltages to its transmission state to cause the ion trap to release at least some of its stored ions therefrom and move them via the front ion mirror towards and into the ELIT, and thereafter controlling a third set of voltages followed by a second set of voltages to its reflection state to trap at least one of the ions passing therethrough and oscillating the at least one trapped ion back and forth between the front ion mirror and the rear ion mirror, each time passing through the charge detection cylinder to induce a corresponding charge therein. may include.

[0008]

[0008] In yet another configuration, a method is provided for operating a charge detection mass analyzer that includes an electrostatic linear ion trap (ELIT) having a charge detection cylinder positioned between a front ion mirror and a rear ion mirror, and an ion trap separate from the front ion mirror. The method can include generating ions from a sample, storing the generated ions in an ion trap, controlling the ion trap to release at least some of the stored ions from the ion trap and move them through the front ion mirror into the ELIT, controlling the rear ion mirror to a reflective state after controlling the ion trap to release the stored ions so that the rear ion mirror reflects incoming ions from the charge detection cylinder back through the charge detection cylinder towards the front ion mirror, and controlling the front ion mirror to a reflective state after controlling the rear ion mirror to its reflective state so that the front ion mirror reflects incoming ions from the charge detection cylinder back through the charge detection cylinder towards the rear ion mirror to trap at least one of the ions released from the ion trap in the ELIT, causing the at least one trapped ion to oscillate back and forth between the front ion mirror and the rear ion mirror, passing through the charge detection cylinder each time and inducing a corresponding charge therein. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a simplified diagram of an ion mass detection system including an embodiment of an electrostatic linear ion trap (ELIT) array with coupled control and measurement components. [Figure 2A] FIG. 2A is a close-up view of an example of one of the ion mirrors of the ELIT array shown in FIG. 1, where the mirror electrodes are controlled to generate an ion-transmitting electric field within the example ion mirror. [Figure 2B]FIG. 2B is a close-up view of another example of one of the ion mirrors of the ELIT array shown in FIG. 1, where the mirror electrodes are controlled to generate an ion-reflecting electric field within the example ion mirror. [Diagram 3] FIG. 3 is a simplified flow chart illustrating an embodiment of a process for controlling the operation of the ELIT array of FIG. 1 to determine mass and charge information of ions. [Figure 4] 4A-4E are simplified diagrams of the ELIT array of FIG. 1 to illustrate the sequential control and operation of multiple ion mirrors according to the process shown in FIG. [Figure 5A] FIG. 5A is a simplified block diagram of an embodiment of an ion separation device including any of the ELIT arrays illustrated and described herein, and shows an example of an ion processing device that may form part of an ion source upstream of the ELIT array(s) and / or may be located downstream of the ELIT array(s) to further process the ion(s) exiting the ELIT array(s). [Figure 5B] FIG. 5B is a simplified block diagram of another embodiment of an ion separation device including any of the ELIT arrays illustrated and described herein, showing an example implementation combining a conventional ion processing device with any of the embodiments of the ion mass detection system illustrated and described herein. [Figure 6] FIG. 6 is a simplified diagram of an ion mass detection system including another embodiment of an electrostatic linear ion trap (ELIT) with combined control and measurement components. [Figure 7A] FIG. 7A is a simplified perspective view of an example embodiment of a single ion steering channel that can be implemented in the ion steering channel array shown in FIG. [Figure 7B] Figure 7B is a simplified perspective view illustrating an example of the mode of operation of the ion steering channel shown in Figure 7A. [Figure 7C]Figure 7C is a simplified perspective view illustrating another example of the mode of operation of the ion steering channel shown in Figure 7A. [Figure 8A] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 8B] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 8C] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 8D] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 8E] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 8F] 8A-8F are simplified diagrams of the ELIT array of FIG. 6 to illustrate examples of control and operation of the ion steering channel array and the ELIT array. [Figure 9] FIG. 9 is a simplified diagram of an ion mass detection system including yet another embodiment of an electrostatic linear ion trap (ELIT) with combined control and measurement components. [Figure 10] FIG. 10 is a simplified diagram of an embodiment of a charge detection mass spectrometer configured for pulsed mode operation. [Figure 11] FIG. 11 is a timing diagram illustrating an exemplary pulse mode operation of the device of FIG. [Figure 12A]FIG. 12A shows a plot of the CDMS mass distribution measured by the apparatus of FIG. 10 for HBV T=4 capsids with sample concentrations of 10 μg / mL and 0.5 μg / mL IT. [Figure 12B] Figure 12B is a log-log plot of the number of ions detected in the mass window from 3.8 MDa to 4.4 MDa shown in Figure 12A during 10,000 trapping events for a range of concentrations from 0.5 μg / mL to 10 μg / mL. [Figure 13A] Figure 13A shows plots of CDMS mass distributions measured by the apparatus of Figure 10 for HBV T=4 capsids with a protein concentration of 1 μg / mL, including distributions measured under standard (i.e., non-pulsed) operation of the apparatus and under pulsed mode operation of the apparatus described herein. [Figure 13B] FIG. 13B shows a plot similar to FIG. 13A, but here the HBV T=4 capsid is at protein concentrations of 0.05 μg / mL and 0.5 μg / mL. [Figure 14] Figure 14 shows plots of CDMS mass distributions measured by the instrument of Figure 10 for HVB capsids with a peak at around 3.0 MDa due to T=3 capsids and a peak at around 4.05 MDa due to T=4 capsids, including distributions measured under standard (i.e., non-pulsed) operation of the instrument (protein concentration was 100 μg / ml) and under pulsed mode operation of the instrument (protein concentration was 1 μg / ml). [Figure 15] FIG. 15 shows plots of CDMS mass distributions measured by the apparatus of FIG. 10 for a pyruvate kinase (PK) solution with peaks due to PK tetramer (230 kDa), octamer (460 kDa), dodecamer (690 kDa), and hexadecamer (920 kDa), including distributions measured under standard (i.e., non-pulsed) operation of the apparatus and distributions measured under pulsed mode operation of the apparatus described herein, with the delay time adjusted to permit permeation of the tetramer and again to permit permeation of the octamer and dodecamer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010]

[0030] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to a number of exemplary embodiments illustrated in the accompanying drawings, and specific language will be used to describe the same.

[0011]

[0031] This disclosure relates to an electrostatic linear ion trap (ELIT) array, including two or more ELIT or ELIT regions and means for controlling the same such that at least two or more ELIT or ELIT regions operate simultaneously to measure the mass-to-charge ratio and charge of at least one ion trapped therein. In this manner, the rate of ion measurement is increased by more than a factor of two over a conventional single ELIT system, with a corresponding reduction in total ion measurement time. In some embodiments, examples of which are described in detail below with respect to Figures 1-4E, the ELIT array may be implemented in the form of two or more ELIT regions arranged in series, i.e., in a cascade, with ion mirrors at opposite ends of each of the two or more cascaded ELIT or ELIT regions being controlled to trap at least one ion in each ELIT or ELIT region in turn and to simultaneously oscillate the trapped ion(s) in the at least two ELIT or ELIT regions back and forth past respective charge detectors arranged therein, such that the mass-to-charge ratio and charge of the trapped ion(s) are measured. In another embodiment, as described in more detail below with respect to Figures 6-10, an ELIT array can be implemented in the form of two or more ELITs arranged in parallel with respect to each other. The ion steering array can be controlled to send at least one ion into each of the parallel-arranged ELITs, either sequentially or simultaneously, and the two or more ELITs are then controlled to cause the trapped ion(s) in the at least two ELITs to oscillate back and forth simultaneously past a charge detector in each ELIT, and the mass-to-charge ratio and charge of the trapped ion(s) are measured.

[0012]

[0032] Referring to FIG. 1, an ion mass detection system 10 is shown that includes an embodiment of an electrostatic linear ion trap (ELIT) array 14 with associated control and measurement components. In the illustrated embodiment, the ion mass detection system 10 includes an ion source 12 operably coupled to the inlet of the ELIT array 14. As described with respect to FIG. 5, the ion source 12 may include, by way of example, any conventional device or apparatus for generating ions from a sample and may further include one or more devices and / or apparatus for separating, collecting, filtering, decomposing, and / or normalizing the ions. As one example, which should not be considered limiting in any way, the ion source 12 may include a conventional electrospray ionization source, a matrix-assisted laser desorption ionization (MALDI) source, or the like, coupled to the inlet of a conventional mass analyzer. The mass analyzer may be of any conventional design, including, by way of example and not limitation, a time-of-flight (TOF) mass analyzer, a reflector mass analyzer, a Fourier transform ion cyclotron resonance (FTICR) mass analyzer, a quadrupole mass analyzer, a triple quadrupole mass analyzer, a magnetic sector mass analyzer, or the like. In any case, the ion outlet of the mass analyzer is operably coupled to the ion inlet of the ELIT array 14. The sample from which ions are generated may be any biological or other material.

[0013]

[0033] In the illustrated embodiment, the ELIT array 14 is provided with, for example, three ELITs or ELIT regions arranged in a cascaded manner, i.e., in series or end-to-end manner. Each of the three individual charge detectors CD1, CD2, CD3 is surrounded by a respective ground cylinder GC1-GC3 and operatively coupled together by opposing mirror electrodes. A first mirror electrode M1 is operatively disposed between the ion source 12 and one end of the charge detector CD1, a second mirror electrode M2 ​​is operatively disposed between the opposite end of the charge detector CD1 and one end of the charge detector CD2, a third mirror electrode M3 is operatively disposed between the opposite end of the charge detector CD2 and one end of the charge detector CD3, and a fourth mirror electrode is operatively disposed at the opposite end of the charge detector CD3. In the illustrated embodiment, each of the ion mirrors M1-M3 defines axially adjacent ion mirror regions R1, R2, and the ion mirror M4 defines, for example, one ion mirror region R1. As an example, the region R2 of the first mirror electrode M1, the charge detector CD1, the region R1 of the second mirror electrode M2, and the space between CD1 and the mirror electrodes M1, M2 together define a first ELIT or ELIT region E1 of the ELIT array 14, the region R2 of the second mirror electrode M2, the charge detector CD2, the region R1 of the third mirror electrode M3, and the space between CD2 and the mirror electrodes M2, M3 together define a second ELIT or ELIT region E2 of the ELIT array 14, and the region R2 of the third mirror electrode M3, the charge detector CD3, the region R1 of the mirror electrode M4, and the space between CD3 and the mirror electrodes M3, M4 together define a third ELIT or ELIT region E3 of the ELIT array 14. It will be understood that in some alternative embodiments, the ELIT array 14 may include a fewer number of cascaded ELITs or ELIT regions, for example, two cascaded ELITs or ELIT regions, and in other alternative embodiments, the ELIT array 14 may include a greater number of cascaded ELITs or ELIT regions, for example, four or more cascaded ELITs or ELIT regions.The construction and operation of any such alternative ELIT array 14 would generally be in accordance with the construction and operation of the embodiment illustrated in FIGS. 1-4E and described below.

[0014]

[0034] In the illustrated embodiment, four corresponding voltage sources V1-V4 are electrically connected to the ion mirrors M1-M4, respectively. Each voltage source V1-V4 includes, by way of example, one or more switchable DC voltage sources that can be controlled or programmed to selectively produce a plurality N of programmable or controllable voltages, where N can be any positive integer. Examples of such voltages are described below with respect to FIGS. 2A and 2B for individually and / or together establishing one of two different operating modes of each ion mirror M1-M4, as described in detail below. In any case, a longitudinal axis 24 extends through the center of the charge detectors CD1-CD3 and the ion mirrors M1-M4, and the longitudinal axis 24 defines an ideal path of travel, and portions thereof, along which ions travel within the ELIT array 14 under the influence of electric fields selectively established by the voltage sources V1-V4.

[0015]

[0035] The voltage sources V1-V4 are illustrated as being electrically connected by a plurality of P signal paths to a conventional processor 16, which includes a memory 18 having instructions stored therein that, when executed by the processor 16, control the voltage sources V1-V4 to produce desired DC output voltages to selectively establish electric fields within the regions R1, R2 of the respective ion mirrors M1-M4. P may be any positive integer. In some alternative embodiments, one or more of the voltage sources V1-V4 may be programmable to selectively produce one or more constant output voltages. In other alternative embodiments, one or more of the voltage sources V1-V4 may be configured to produce one or more time-varying output voltages of any desired shape. It will be appreciated that in alternative embodiments, more or fewer voltage sources may be electrically connected to the mirror electrodes M1-M4.

[0016]

[0036] Each charge detector CD1-CD3 is electrically connected to an input of a corresponding one of three charge sensitive preamplifiers CP1-CP3, and a signal output of each charge preamplifier CP1-CP3 is electrically connected to the processor 16. Each charge preamplifier CP1-CP3 is, by way of example, conventionally operable to receive a detection signal detected by a respective one of the charge detectors CD1-CD3, produce a corresponding charge detection signal therefor, and provide the charge detection signal to the processor 16. The processor 16 is then, by way of example, operable to receive and digitize the charge detection signal produced by each of the charge preamplifiers CP1-CP3, and store the digitized charge detection signal in the memory 18. The processor 16 is further, by way of example, coupled to one or more peripheral devices 20 (PD) for providing signal input(s) to and / or from the processor 16. In some embodiments, the peripheral device 20 includes at least one of a conventional display monitor, a printer, and / or other output device, and in such embodiments, the memory 18 stores instructions that, when executed by the processor 16, cause the processor 16 to control one or more such output peripheral devices 20 to display and / or record an analysis of the stored and digitized charge detection signals. In some embodiments, a conventional microchannel plate (MP) detector 22 may be disposed at the ion outlet of the ELIT array 14, i.e., the ion outlet of the ion mirror M4, and may be electrically connected to the processor 16. In such embodiments, the microchannel plate detector 22 is operative to provide a detection signal to the processor 16 that corresponds to the detected ions and / or neutrals.

[0017]

[0037] As will be explained in more detail below, voltage sources V1-V4 are controlled, by way of example, to direct ions from ion source 12 into ELIT array 14, which selectively traps and confines at least one ion to oscillate within each of three separate ELITs or ELIT regions E1-E3, and causes each trapped ion(s) to repeatedly pass through a respective one of charge detectors CD1-CD3 of each of the three ELITs or ELIT regions E1-E3. A plurality of charge and oscillation period values ​​are measured at each charge detector CD1-CD3, and the recorded results are processed to determine mass-to-charge ratio and mass values ​​for the ion(s) trapped in each of the three ELITs or ELIT regions E1-E3. Depending on several factors including, but not limited to, the dimensions of the three ELIT or ELIT regions E1-E3, the ion oscillation frequency and residence time of the ion in each of the three ELIT or ELIT regions E1-E3, the trapped ion(s) will oscillate simultaneously in at least two of the three ELIT or ELIT regions E1-E3, such that in a typical implementation in each of the three ELIT or ELIT regions E1-E3, measurements of the charge and mass-to-charge ratio of the ion can be controlled simultaneously from at least two of the three ELIT or ELIT regions E1-E3.

[0018]

[0038] 2A and 2B, an embodiment of one of the ion mirrors MX of the ELIT array 14 of FIG. 1 is shown, where X=1-4, illustrating its construction and operation. In each of FIGS. 2A and 2B, the example ion mirror MX includes seven spaced apart conductivity type mirror electrodes arranged in a cascade. For each of the ion mirrors M2-M4, the first electrode 301 is coupled to a charge detector CD X-1 The gland cylinder GC is placed around each of the X-1It is formed by. On the other hand, the first electrode 301 of the ion mirror M1 is formed by the ion emission port of the ion source 12 (IS), or as part of the ion focusing or transition stage between the ion source 12 and the ELIT array 14. FIG. 2B illustrates the former, and FIG. 2A illustrates the latter. In any case, the first mirror electrode 301 defines an opening A1 passing through its center, which serves as an ion intake port to the corresponding ion mirror MX and / or an ion emission port from the corresponding ion mirror MX. The opening A1 is, for example, conical in shape, which is GC X-1 or between the inner and outer surfaces of the GC X-1 or from the first diameter P1 defined by the inner surface of the IS to GC X-1 or up to the extended second diameter P2 on the outer surface of the IS, increasing linearly. The first mirror electrode 301 has, for example, a thickness of D1.

[0019]

[0039] The second mirror electrode 302 of the ion mirror MX is spaced from the first mirror electrode 301 and defines a passage therethrough with a diameter of P2. The third mirror electrode 303 is spaced from the second mirror electrode 302 and similarly defines a passage therethrough with a diameter of P2. The second and third mirror electrodes 302 and 303 have, for example, equal thicknesses of D2≧D1. The fourth mirror electrode 304 is spaced from the third mirror electrode 303. The fourth mirror electrode 304 defines a passage therethrough with a diameter of P2 and has, for example, a thickness of D3≒3D2. The plate or grid 30A is, for example, centrally disposed within the passage of the fourth mirror electrode 304 and defines a central opening CA with a diameter of P3 therethrough. In the exemplary embodiment, P3<P1, but in other embodiments, P3 can be made greater than or equal to P1. The fifth mirror electrode 305 is spaced from the fourth mirror electrode 304, and the sixth mirror electrode 306 is spaced from the fifth mirror electrode 305. For example, the fifth and sixth mirror electrodes 305 and 306 are the same as the third and second mirror electrodes 303 and 302, respectively.

[0020]

[0040] For each of the ion mirrors M1-M3, the seventh mirror electrode 307 is connected to a charge detector CD X The gland cylinder GC is placed around each of the X On the other hand, the seventh mirror electrode 307 of the ion mirror M4 is the last in the sequence and can therefore be a stand-alone electrode. In any case, the seventh mirror electrode 307 defines an aperture A2 through its centre, which serves as an entrance and / or exit for ions into and / or from the ion mirror MX. The aperture A2 is, by way of example, a mirror image of the aperture A1 and is conical in shape, which allows the GC X Between the outer and inner surfaces of GC X The expanded diameter P2 to GC is determined by the outer surface of X The seventh mirror electrode 307 has a thickness of D1, by way of example. In some embodiments, as shown by way of example in FIG. 1, the last ion mirror in the sequence, i.e., M4 in FIG. 2, may terminate at the plate or grid 30A, such that M4 includes only the mirror electrodes 301-303 and only the portion of the mirror electrode 304 that includes the plate or grid 30A. In such embodiments, a central aperture CA of M4 defines an ion exit passage from the ELIT array 14.

[0021]

[0041] The mirror electrodes 301-307 are illustratively equally spaced apart from one another by a space S1. Such space S1 of the mirror electrodes 301-307 may be a void or vacuum gap in some embodiments, and in other embodiments such space S1 may be filled with one or more non-conductive or insulating materials. The mirror electrodes 301-307 are axially aligned, and therefore collinear, such that the longitudinal axis 24 passes through the center of each aligned passageway and through the center of the openings A1, A2, and CA. In embodiments in which the space S1 includes one or more non-conductive materials, such materials similarly define respective passageways therethrough, which are axially aligned, and therefore collinear, with the passageways defined through the mirror electrodes 301-307, and have a diameter equal to or greater than P2.

[0022]

[0042] In each of the ion mirrors M1-M4, a region R1 is defined between an aperture A1 in the mirror electrode 301 and a central aperture CA defined through the plate or grid 30A. In each of the ion mirrors M1-M3, an adjacent region R2 is defined between a central aperture CA defined through the plate or grid 30A and an aperture A2 in the mirror electrode 307.

[0023]

[0043] Within each of ELIT or ELIT regions E1 - E3, each of charge detectors CD1 - CD3, each in the form of a long conductive cylinder, is disposed between corresponding ones of ion mirrors M1 - M4, spaced only by space S2. By way of example, S2 > S1, although in an alternative embodiment S2 can be made less than or equal to S1. In any case, each of charge detection cylinders CD1 - CD3, by way of example, defines a passage of diameter P4 axially therethrough, and each of charge detection cylinders CD1 - CD3 is oriented with respect to ion mirrors M1 - M4 such that longitudinal axis 24 extends through the center of that passage. In the exemplary embodiment, P1 < P4 < P2, although in an alternative embodiment, the diameter of P4 can be made less than or equal to P1, or greater than or equal to P2. Each of charge detection cylinders CD1 - CD3 is, by way of example, disposed within the field - free region of respective ones of ground cylinders GC1 - GC3, each of ground cylinders GC1 - GC3 being disposed between and forming part of respective ones of ion mirrors M1 - M4 as described above. In operation, ground cylinders GC1 - GC3 are, by way of example, controlled such that first and seventh electrodes 301 and 307 are always at ground potential. In some alternative embodiments, either or both of first and seventh electrodes 301 and 307 in one or more of ion mirrors M1 - M4 can be set to any desired DC reference potential, and in another alternative embodiment, either or both of first and seventh electrodes 301 and 307 in one or more of ion mirrors M1 - M4 can be electrically connected to a switchable DC or other time - varying voltage source.

[0024]

[0044] As briefly described above, voltage sources V1-V4 are controlled, by way of example, to transmit ions from ion source 12 into ELIT array 14 and to selectively trap and oscillate at least one ion in each of three individual ELITs or ELIT regions E1-E3, and to cause each trapped ion(s) to repeatedly pass through each of charge detectors CD1-CD3 in each of the three ELITs or ELIT regions E1-E3. Charge and oscillation period values ​​are measured at each of charge detectors CD1-CD3 each time each oscillating ion(s) passes through it. The measurements are recorded and the recorded results are processed to determine mass-to-charge ratio and mass values ​​for the trapped ion(s) in each of the three ELITs or ELIT regions E1-E3.

[0025]

[0045] At least one ion is trapped and caused to oscillate between opposing regions of each ion mirror M1-M4 by controlling voltage sources V1-V4 to selectively establish ion transmitting and reflecting electric fields in regions R1, R2 of ion mirror M1-M4 within each of the ELIT or ELIT regions E1-E3 of ELIT array 14. In this regard, each voltage source VX is, by way of example, configured in one embodiment to generate seven DC voltages DC1-DC7 and to supply each of the voltages DC1-DC7 to a respective one of the mirror electrodes 301-307 of a respective ion mirror MX. In some embodiments in which one or more of the mirror electrodes 301-307 are caused to be held at ground potential at all times, one or more such mirror electrodes 301-307 may instead be electrically connected to a ground reference of voltage source VX, and the corresponding one or more voltage outputs DC1-DC7 may be omitted. Alternatively or additionally, in embodiments in which any two or more of the mirror electrodes 301-307 are controlled to the same non-zero DC value, any such two or more mirror electrodes 301-307 can be electrically connected to one of the voltage outputs DC1-DC7, and the redundant output voltages DC1-DC7 can be omitted.

[0026]

[0046] As shown by way of example in Figures 2A and 2B, each ion mirror MX can be controlled by selective application of voltages DC1-DC7 between an ion transmission mode (Figure 2A) in which voltages DC1-DC7 produced by voltage source VX establish an ion transmission electric field in each of regions R1, R2 of the ion mirror MX, and an ion reflection mode (Figure 2AB) in which voltages DC1-DC7 produced by voltage source VX establish an ion trapping or reflection electric field in each of regions R1, R2 of the ion mirror MX. In the ion transmission mode, as shown by way of example in Figure 2A, voltages DC1-DC7 are selected to establish an ion transmission electric field TEF1 in region R1 of the ion mirror MX and another ion transmission electric field TEF2 in region R2 of the ion mirror MX. Ion transmission electric fields TEF1 and TEF2 are established, for example, in the ion mirror MX to focus ions towards a central longitudinal axis 24, maintaining narrow ion trajectories along the axis 24 through the ELIT array 14, while also accelerating ions moving in either direction through both regions R1, R2 of the ion mirror MX. In the ion reflection mode, voltages DC1-DC7 are selected to establish an ion trapping or reflection electric field REF1 in region R1 of the ion mirror MX, and to establish another ion trapping or reflection electric field REF2 in region R2 of the ion mirror MX, as shown by way of example in FIG. 2B. The ion trapping or reflection electric fields REF1 and REF2 are established, for example, such that one or more ions moving axially into the respective regions R1, R2 towards the central aperture CA of MX are reversed and transmitted by the reflection electric fields REF1, REF2 in the opposite direction axially away from the central aperture CA. Each of the ion reflecting fields REF1, REF2 does this by first slowing down and stopping, i.e. trapping, one or more ions and moving them into a respective region R1, R2 of the ion mirror MX and then accelerating such one or more ions back in the opposite direction through the respective region R1, R2, causing the one or more ions to move away from the respective region R1, R2 in the opposite direction that they entered the respective region R1, R2.That is, along a central longitudinal axis 24, a charge detection cylinder CD. X-1 Ions moving from the charge detector 14 to the charge detector 15 in region R1 of the ion mirror MX are reflected by the reflected electric field REF1 along the central longitudinal axis 24 into the charge detector cylinder CD X-1 and other ions traveling along the central longitudinal axis 24 from the charge detection cylinder CDX into region R2 of the ion mirror MX are reflected back into the charge detection cylinder CDX by the reflected electric field REF2 along the central longitudinal axis 24. An example set of output voltages DC1-DC7 produced by each of the voltage sources V1-V4 to control a corresponding one of the ion mirrors M1-M4 into the above-mentioned ion transmission and ion reflection modes is shown in Table 1 below. It will be understood that the following values ​​for DC1-DC7 are provided by way of example only, and that other values ​​can alternatively be used for one or more of DC1-DC7.

[0027] [Table 1]

[0028]

[0047] 3, there is shown a simplified flow chart of a process 100 for controlling voltage sources V1-V4 to selectively and sequentially control ion mirrors M1-M4 between their above-mentioned transmission and reflection modes, which causes ions to be transmitted from the ion source 12 into the ELIT array 14, which in turn causes at least one ion to be selectively trapped, confined and oscillated in each of three separate ELITs or ELIT regions E1-E3, and each trapped ion(s) to repeatedly pass through each of the charge detectors CD1-CD3 of each of the three ELITs or ELIT regions E1-E3. Charge and oscillation period values ​​are measured and recorded at each of the charge detectors CD1-CD3 each time each oscillating ion(s) passes therethrough, and then an ion mass value is determined based on the recorded data. In the illustrated embodiment, the process 100 is illustratively stored in the memory 18 in the form of instructions, which, when executed by the processor 16, cause the processor 16 to perform the functions previously described. In alternative embodiments in which one or more of the voltage sources V1-V4 are programmable independently of the processor 16, one or more features of the process 100 may be performed, in whole or in part, by one or more such programmable voltage sources V1-V4. However, for purposes of this disclosure, the process 100 will be described as being performed solely by the processor 16. Although, with the aid of Figures 4A-4E, the process 100 will be described as acting on one or more positively charged ions, it will be understood that the process 100 may alternatively act on one or more negatively charged ions.

[0029]

[0048] 4A, the process 100 begins at step 102, where the processor 16 is operable to control the voltage sources V1-V4 to set respective voltages DC1-DC7 to operate all of the ion mirrors M1-M4 in an ion transmission mode such that a transmission electric field TEF1, TEF2 established at each respective region R1, R2 accelerates ions through them. In one exemplary embodiment, the voltage sources V1-V4 are illustratively controlled at step 102 of the process 100 to produce voltages DC1-DC7 according to an all-pass transmission mode as shown in Table 1 above. In either case, with each of the voltage sources V1-V4 set at step 102 to control the ion mirrors M1-M4 to operate in an ion transmission mode, ions entering M1 from the ion source 12 pass through all of the ion mirrors M1-M4 and all of the charge detectors CD1-CD3 and exit M4, as shown by the exemplary ion trajectory 50 depicted in FIG. 4A. Such control of ion mirrors M1-M4 into their respective transmission modes thus draws one or more ions from the ion source 12 into the entire ELIT array 14, as shown in Figure 4A. The ion trajectory 50 depicted in Figure 4A can represent, by way of example, a single ion or a group of ions.

[0030]

[0049] Following step 102, process 100 proceeds to step 104, where processor 16 is operable to pause and determine when to proceed to step 106. In one embodiment of step 102, ELIT array 14 is, by way of example, controlled in a "random trapping mode" in which ion mirrors M1-M4 are maintained in their transmission mode for a selected period of time during which one or more ions generated by ion source 12 are expected to enter and travel through ELIT array 14. As one non-limiting example, when operating in random trapping mode, the selected period of time that processor 16 spends in step 104 before proceeding to step 106 is on the order of 1-3 milliseconds (ms), depending on the axial length of ELIT array 14 and the velocity of ions entering ELIT array 14, although it will be understood that in other embodiments such selected period of time may be longer than 3 ms or shorter than 1 ms. Process 100 follows the NO branch of step 104 and loops back to the start of step 104 until the selected time period has elapsed. After the selected time period has elapsed, process 100 follows the YES branch of step 104 and proceeds to step 106. In some alternative embodiments of step 104, such as those including a microchannel plate detector 22, processor 16 can be configured to proceed to step 106 only after one or more ions have been detected by detector 22, with or without a further additional delay period, to ensure that ions have been transmitted through ELIT array 14 before proceeding to step 106. In other alternative embodiments, ELIT array 14 can be controlled by processor 16, by way of example, in a "triggered trapping mode," in which ion mirrors M1-M4 are held in their transmission mode until at least one ion is detected by charge detector CD3. Until such detection, process 100 follows the NO branch of step 104 and loops back to the start of step 104.Detection of at least one ion at charge detector CD3 by processor 16 indicates at least one ion passing through charge detector CD3 towards ion mirror M4 and acts as a trigger event causing processor 16 to follow the YES branch of step 104 to step 106 of process 100.

[0031]

[0050] Following the YES branch of step 104, and referring to FIG. 4B, the processor 16 is operable in step 106 to control the voltage source V4 to set its output voltages DC1-DC7 to change or switch the operation of the ion mirror M4 from an ion transmission mode of operation to an ion reflection mode of operation in which an ion reflection field R41 is established within the region R1 of M4. The ion reflection field R41, as described above, operates to reflect one or more ions entering the region R1 of M4 back towards the ion mirror M3 (and through the charge detector CD3), as previously described with respect to FIG. 2B. The output voltages DC1-DC7 produced by the voltage sources V1-V3, respectively, are not changed in step 106, and thus each of the ion mirrors M1-M3 remains in the ion transmission mode. As a result, one or more ions traveling within the ELIT array 14 towards ion mirror M4 are reflected back towards ion mirror M3 and transmitted along axis 24 towards the ion inlet of M1, as shown by the exemplary ion trajectory 50 in FIG. 4B.

[0032]

[0051] Following step 106, process 100 proceeds to step 108, where processor 16 is operable to pause and determine when to proceed to step 110. In embodiments of step 108 in which ELIT array 14 is controlled by processor 16 in a random trapping mode, ion mirrors M1-M3 are held in their transmission mode in step 108 for a selected period of time during which one or more ions may enter the ELIT or ELIT region E3. As one non-limiting example, when operating in a random trapping mode, the selected period of time that processor 16 spends in step 108 before proceeding to step 110 is on the order of 0.1 milliseconds (ms), although it will be understood that in other embodiments such selected period of time may be longer or shorter than 0.1 ms. Until the selected period of time has elapsed, process 100 follows the NO branch of step 108 and loops back to the start of step 108. After the selected time period has elapsed, process 100 follows the YES branch of step 108 and proceeds to step 110. In an alternative embodiment of step 108 in which the ELIT array 14 is controlled by processor 16 in a triggered trapping mode, ion mirrors M1-M3 are held in their ion transmission mode until at least one ion is detected at charge detector CD3. Until such detection, process 100 follows the NO branch of step 108 and loops back to the start of step 108. Detection of at least one ion at charge detector CD3 by processor 16 ensures that at least one ion is traveling through charge detector CD3 and serves as a trigger event causing processor 16 to follow the YES branch of step 108 and proceed to step 110 of process 100.

[0033]

[0052] Following the YES branch of step 108, and referring to Figure 4C, the processor 16 is operable in step 110 to control the voltage source V3 to set its output voltages DC1-DC7 to change or switch the operation of the ion mirror M3 from an ion transmission mode of operation to an ion reflection mode of operation in which an ion reflection electric field R31 is established in region R1 of M3 and an ion reflection electric field R32 is established in region R2 of M3. As a result, at least one ion is trapped in the ELIT or ELIT region E3, and due to the reflection electric fields R32 and R41 established in region R2 of mirror M3 and region R1 of mirror M4, respectively, the at least one trapped ion oscillates between M3 and M4, each time passing through the charge detection cylinder CD3, as shown by the ion trajectory 503 illustrated in Figure 4C. Each time at least one ion passes through the charge detection cylinder CD3, it induces a charge in the cylinder CD3, which is detected by the charge preamplifier CP3 (see FIG. 1). In step 112, as at least one ion oscillates back and forth between the ion mirrors M3, M4 and through the charge detection cylinder CD3, the processor 16 is operable to record the amplitude and timing of each such CD3 charge detection event and store it in memory 18.

[0034]

[0053] As described above, ion reflecting electric field R31 operates to reflect one or more ions entering region R1 of M3 back towards ion mirror M2 (and through charge detector CD2), as previously described with respect to FIG. 2B. The output voltages DC1-DC7 produced by each of voltage sources V1-V2 do not change in steps 110 and 112, and therefore each of ion mirrors M1-M2 remains in the ion transmission mode. As a result, one or more ions traveling within the ELIT array 14 towards ion mirror M3 will follow the ion trajectory 50 illustrated in FIG. 4C. 1,2 As shown by , it is reflected back towards ion mirror M2 and transmitted along axis 24 towards the ion inlet of M1.

[0035]

[0054] Following steps 110 and 112, process 100 proceeds to step 114, where processor 16 is operable to pause and determine when to proceed to step 116. In embodiments of step 114 in which ELIT array 14 is controlled by processor 16 in a random trapping mode, ion mirrors M1-M2 are held in their transmission mode in step 114 for a selected period of time during which one or more ions may enter the ELIT or ELIT region E2. As one non-limiting example, the selected period of time that processor 16 spends in step 114 before proceeding to step 116 when operating in a random trapping mode is on the order of 0.1 milliseconds (ms), although it will be understood that such selected period of time may be longer or shorter than 0.1 ms in other embodiments. Until the selected period of time has elapsed, process 100 follows the NO branch of step 114 and loops back to the start of step 108. After the selected time period has elapsed, process 100 follows the YES branch of step 114 and proceeds to step 116. In an alternative embodiment of step 114 in which the ELIT array 14 is controlled by processor 16 in a triggered trapping mode, ion mirrors M1-M2 are held in their ion transmission mode until at least one ion is detected at charge detector CD2. Until such detection, process 100 follows the NO branch of step 114 and loops back to the start of step 114. Detection of at least one ion at charge detector CD2 by processor 16 ensures that at least one ion is traveling through charge detector CD2 and serves as a trigger event causing processor 16 to follow the YES branch of step 114 and proceed to step 116 of process 100.

[0036]

[0055] As described above, ion reflecting field R21 operates to reflect one or more ions entering region R1 of M2 back towards ion mirror M1 (and through charge detector CD1) as previously described with respect to FIG. 2B. The output voltages DC1-DC7 produced by voltage source V1 do not change in steps 116 and 118, and thus ion mirror M1 remains in the ion transmission mode. As a result, one or more ions traveling within ELIT array 14 towards ion mirror M2 are reflected back towards ion mirror M1 and transmitted along axis 24 towards the ion inlet of M1, as shown by ion trajectory 501 illustrated in FIG. 4D.

[0037]

[0056] Following the YES branch of step 114, and if at least one ion in the ELIT or ELIT region E3 continues to oscillate back and forth between ion mirrors M3 and M4 through charge detection cylinder CD3, process 100 proceeds to step 116. Referring to FIGURE 4D, in step 116, processor 16 is operable to control voltage source V2 to set its output voltage DC1-DC7 to change or switch operation of ion mirror M2 from an ion transmission mode of operation to an ion reflection mode of operation in which an ion reflection electric field R21 is established in region R1 of M2 and an ion reflection electric field R22 is established in region R2 of M2. As a result, at least one ion is trapped in the ELIT or ELIT region E2, and due to the reflected electric fields R22 and R31 established in the region R2 of mirror M2 and the region R1 of mirror M3, respectively, the at least one trapped ion oscillates between M2 and M3, passing each time through the charge detection cylinder CD2, as illustrated by the ion trajectory 502 depicted in FIG. 4D. Each time the at least one ion passes through the charge detection cylinder CD2, it induces a charge in the cylinder CD2, which is detected by the charge preamplifier CP2 (see FIG. 1). In step 118, as the at least one ion oscillates back and forth between the ion mirrors M2, M3 and through the charge detection cylinder CD2, the processor 16 is operable to record the amplitude and timing of each such CD2 charge detection event and store it in the memory 18. That is, following step 116, at least one ion oscillates back and forth between ion mirrors M3 and M4 through the ELIT or charge detection cylinder CD3 of ELIT region E3, while at the same time, at least one other ion oscillates back and forth between ion mirrors M2 and M3 through the ELIT or charge detection cylinder CD2 of ELIT region E2.

[0038]

[0057] Following steps 116 and 118, process 100 proceeds to step 120, where processor 16 is operable to pause and determine when to proceed to step 122. In an embodiment of step 120 in which ELIT array 14 is controlled by processor 16 in a random trapping mode, ion mirror M1 is held in its transmission mode in step 120 for a selected period of time during which one or more ions may enter the ELIT or ELIT region E1. As one non-limiting example, when operating in a random trapping mode, the selected period of time that processor 16 spends in step 120 before proceeding to step 122 is on the order of 0.1 milliseconds (ms), although it will be understood that in other embodiments such selected period of time may be longer or shorter than 0.1 ms. Until the selected period of time has elapsed, process 100 follows the NO branch of step 120 and loops back to the start of step 120. After the selected time period has elapsed, process 100 follows the YES branch of step 120 and proceeds to step 122. In an alternative embodiment of step 120 in which the ELIT array 14 is controlled by processor 16 in a triggered trapping mode, ion mirror M1 is held in its ion transmission mode until at least one ion is detected at charge detector CD1. Until such detection, process 100 follows the NO branch of step 120 and loops back to the start of step 120. Detection of at least one ion at charge detector CD1 by processor 16 ensures that at least one ion is traveling through charge detector CD1 and serves as a trigger event causing processor 16 to follow the YES branch of step 120 and proceed to step 122 of process 100.

[0039]

[0058] Following the YES branch of step 120, if at least one ion in the ELIT or ELIT region E3 continues to oscillate back and forth between ion mirrors M3 and M4 through charge detection cylinder CD3 and at least one other ion in the ELIT or ELIT region E2 simultaneously continues to oscillate back and forth between ion mirrors M2 and M3 through charge detection cylinder CD2, process 100 proceeds to step 122. Referring to FIG. 4E, at step 122, processor 16 is operable to control voltage source V1 to set its output voltage DC1-DC7 to change or switch operation of ion mirror M1 from an ion transmission mode of operation to an ion reflection mode of operation in which an ion reflection electric field R11 is established in region R1 of M1 and an ion reflection electric field R12 is established in region R1 of M1. As a result, at least one ion is trapped in the ELIT or ELIT region E1, and due to the reflected electric fields R12 and R21 established in the region R2 of mirror M1 and the region R2 of mirror M2, respectively, the at least one trapped ion oscillates between M1 and M2, passing each time through the charge detection cylinder CD1, as illustrated by the ion trajectory 501 depicted in FIG. 4E. Each time the at least one ion passes through the charge detection cylinder CD1, it induces a charge in the cylinder CD1, which is detected by the charge preamplifier CP1 (see FIG. 1). In step 124, as the at least one ion oscillates back and forth between the ion mirrors M1, M2 and through the charge detection cylinder CD1, the processor 16 is operable to record the amplitude and timing of each such CD1 charge detection event and store it in the memory 18. That is, following step 122, at least one ion oscillates back and forth between ion mirrors M3 and M4 through charge detection cylinder CD3 of the ELIT or ELIT region E3, while at the same time, at least one other ion oscillates back and forth between ion mirrors M2 and M3 through charge detection cylinder CD2 of the ELIT or ELIT region E2, and while at the same time, at least one other ion oscillates back and forth between ion mirrors M1 and M2 through charge detection cylinder CD1 of the ELIT or ELIT region E1.

[0040]

[0059] Following steps 122 and 124, process 100 proceeds to step 126 where processor 16 is operable to pause and determine when to proceed to step 128. In one embodiment, processor 16 is configured, i.e., programmed, to allow ions to oscillate back and forth simultaneously through each of the ELITs or ELIT regions E1-E3 for a selected period of time during which ion detection events by each of charge detectors CD1-CD3 are recorded by processor 16, i.e., the total ion cycle measurement time. As one non-limiting example, the selected period of time that processor 16 spends in step 126 before proceeding to step 128 is on the order of 100-300 milliseconds (ms), although it will be appreciated that in other embodiments such selected period of time may be longer than 300 ms or shorter than 100 ms. Until the selected period of time has elapsed, process 100 follows the NO branch of step 126 and loops back to the start of step 126. After the selected time period has elapsed, the process 100 follows the YES branch of step 126 and proceeds to steps 128 and 140. In some alternative embodiments of the process 100, the voltage sources V1-V4 may be controlled by the processor 16 to, for example, allow the ion(s) to oscillate back and forth through the charge detectors CD1-CD3 a selected number of measurement cycles, i.e., a total number of measurement cycles, in which an ion detection event by each of the charge detectors CD1-CD3 is recorded by the processor 16 in step 126. The process 100 follows the NO branch of step 126 and loops back to the start of step 126 until the processor has counted a selected number of ion detection events in one or more of the charge detectors CD1-CD3. The detection of the selected number of ion detection events by the processor 16 serves as a triggering event that causes the processor 16 to follow the YES branch of step 126 and proceed to steps 128 and 140 of the process 100.

[0041]

[0060] Following the YES branch of step 126, in step 128 the processor 16 is operable to control the voltage sources V1-V4 to set respective output voltages DC1-DC7 to change or switch the operation of all of the ion mirrors M1-M4 from an ion reflecting mode of operation to an ion transmitting mode of operation in which each of the ion mirrors M1-M4 operates to allow ions to pass therethrough. By way of example, in step 128 of process 100, voltage sources V1-V4 are controlled to produce voltages DC1-DC7 according to, by way of example, the all-pass transmission mode illustrated in Table 1 above, which re-establishes the ion trajectory 50 illustrated in FIG. 4A , in which (i) all ions within the ELIT array 14 are transmitted through and out of the ELIT array 14 under the influence of ion transmission electric fields TEF1, TEF2 established in each of the ion mirrors M1-M4, and (ii) all ions entering M1 from the ion source 12 pass through all of the ion mirrors M1-M4 and all of the charge detectors CD1-CD3.

[0042]

[0061] Following step 128, in step 130, the process is operable to pause for a selected period of time to allow ions contained within the ELIT array 14 to transmit out of the ELIT array 14. As one non-limiting example, the selected period of time that the processor 16 spends in step 130 before looping back to step 102 to restart the process 100 is on the order of 1-3 milliseconds (ms), although it will be understood that in other embodiments such selected period of time may be longer than 3 ms or shorter than 1 ms. Until the selected period of time has elapsed, the process 100 follows the NO branch of step 130 and loops back to the start of step 130. After the selected period of time has elapsed, the process 100 follows the YES branch of step 130 and loops back to step 102 to restart the process 100.

[0043]

[0062] Alternatively, following the YES branch of step 126, process 100 may further proceed to step 140 to analyze the data collected during steps 112, 118, and 124 of process 100 just described. In an exemplary embodiment, data analysis step 140 illustratively includes step 142, in which processor 16 is operable to calculate a Fourier transform of the recorded set of charge detection signals provided to and stored in each of charge preamplifiers CP1-CP3. By way of example, processor 16 is operable to perform step 142 using any conventional Digital Fourier Transform (DTF) technique, such as, by way of example and not limitation, a conventional Fast Fourier Transform (FFT) algorithm or the like. In any event, the processor 16 is operable in step 142 to calculate three Fourier transforms, FT1, FT2 and FT3, FT1 being the Fourier transform of the set of charge detection signals provided and recorded by the first charge preamplifier CP1 and thus corresponding to the charge detection events detected by the ELIT or charge detection cylinder CD1 of the ELIT area E1, FT2 being the Fourier transform of the set of charge detection signals provided and recorded by the first charge preamplifier CP2 and thus corresponding to the charge detection events detected by the ELIT or charge detection cylinder CD2 of the ELIT area E2, and FT3 being the Fourier transform of the set of charge detection signals provided and recorded by the first charge preamplifier CP3 and thus corresponding to the charge detection events detected by the ELIT or charge detection cylinder CD3 of the ELIT area E3.

[0044]

[0063] Following step 142, the process 100 proceeds to step 144, where the processor 16 is operable to calculate three sets of ion mass-to-charge ratio values ​​(m / z1, m / z2, m / z3), ion charge values ​​(z1, z2, z3), and ion mass values ​​(m1, m2, m3), each as a function of a respective one of the calculated Fourier transform values ​​(FT1, FT2, FT3). Thereafter, in step 146, the processor 16 is operable to store the calculated results in memory 18 and / or to control one or more of the peripheral devices 20 to display the results for viewing and / or further analysis.

[0045]

[0064] The mass-to-charge ratio (m / z) of an ion (one or more) oscillating back and forth between the opposing ion mirrors in either the ELIT or ELIT regions E1-E3 is given by m / z=C / ff 2 is generally understood to be inversely proportional to the square of the fundamental frequency ff of the oscillating ion (one or more) according to: where C is a constant that is a function of the ion energy and also of the dimensions of the individual ELIT or ELIT region, and the fundamental frequencies ff are determined directly from the respective calculated Fourier transforms; that is, ff1 is the fundamental frequency of FT1, ff2 is the fundamental frequency of FT2, and ff3 is the fundamental frequency of FT3. Typically, C is determined using conventional ion trajectory simulations. In any case, the value z of the ion charge is proportional to the magnitude of FT, FT, which takes into account the number of ion oscillation cycles. MAG The ion mass m is then calculated as the product of m / z and z. That is, for a set of recorded charge detection signals provided by the first charge preamplifier CP1, the processor 16 calculates in step 144: m / z1=C / ff1 2 And z1=F(FT MAG1 For the set of recorded charge detection signals provided by the second charge preamplifier CP2, the processor 16 is similarly operable to calculate m / z2=C / ff2 at step 144. 2And z2 = F(FT MAG2 ) and m2=(m / z2)(z2), and for the set of recorded charge detection signals provided by the third charge preamplifier CP3, the processor 16 similarly calculates in step 144 m / z3=C / ff3 2 And z3=F(FT MAG3 ), and m3=(m / z3)(z3).

[0046]

[0065] 5A, there is shown a simplified block diagram of an embodiment of an ion isolation apparatus 60, which may include any of the ELIT arrays 14, 205, 302 illustrated and described herein, which may include any of the ion mass detection systems 10, 200, 300 illustrated and described herein, which may include any number of ion processing devices that may form part of the ion source 12 upstream of the ELIT array(s) and / or which may be disposed downstream of the ELIT array(s) for further processing of the ion(s) exiting the ELIT array(s). In this regard, in FIG. 5A, the ion source 12 is shown to include a number Q of ion source stages IS1-IS that may be or form part of the ion source 12. Q Alternatively or additionally, ion processing device 70 is illustrated in FIG. 5A as being coupled to the ion outlet of ELIT array 14, 205, 302, and ion processing device 70 may include any number of ion processing stages OS1-OS R where R can be any positive integer.

[0047]

[0066] Focusing the ion source 12 allows the source of ions entering the ELIT 10 to be separated into ion source stages IS1-IS2 for filtering ions (e.g., according to one or more molecular properties such as ion mass, ion mass-to-charge ratio, ion mobility, ion retention time, etc.), fragmenting or separating ions, standardizing ion charge states, and the like. Q It will be understood that the ion source 12 may be or include a conventional source of ions in the form of one or more of the following: a conventional ion source, an ion separator, and / or an ion processing device, and may further include one or more conventional devices for separating ions according to one or more molecular characteristics (e.g., according to ion mass, ion mass-to-charge ratio, ion mobility, ion retention time, etc.) and / or one or more conventional ion processing devices for collecting and / or storing ions (e.g., one or more quadrupole ion traps, hexapole ion traps, and / or other ion traps). It will be understood that the ion source 12 may include any one or any combination of any such conventional ion sources, ion separators, and / or ion processing devices in any order, and some embodiments may include a plurality of any such conventional ion sources, ion separators, and / or ion processing devices, adjacent or spaced apart.

[0048]

[0067] Turning now to ion processing apparatus 70, apparatus 70 includes ion processing stages OS1-OS2 for filtering ions (e.g., according to one or more molecular properties such as ion mass, ion mass-to-charge ratio, ion mobility, ion retention time, etc.), for fragmenting or separating ions, for standardizing ion charge states, and the like. RIt will be understood that the ion processing device 70 may be or include one or more conventional devices for separating ions according to one or more molecular properties (e.g., according to ion mass, ion mass-to-charge ratio, ion mobility, ion retention time, etc.) in the form of one or more of the following: and / or may be or include one or more conventional ion processing devices for collecting and / or storing ions (e.g., one or more quadrupole ion traps, hexapole ion traps, and / or other ion traps). It will be understood that the ion processing device 70 may include any one or any combination of any such conventional ion separation devices and / or ion processing devices in any order, and some embodiments may include a plurality of any such conventional ion separation devices and / or ion processing devices, adjacent or spaced apart. In any implementation including one or more mass analyzers, any one or more such mass analyzers may be implemented in any manner previously described with respect to FIG.

[0049]

[0068] As one particular implementation of the ion separation device 60 illustrated in FIG. 5A, which should not be considered limiting in any way, the ion source 12 illustratively includes three stages and the ion treatment device 70 is omitted. In this illustrative implementation, the ion source stage IS1 is a conventional source of ions, such as electrospray, MALDI, etc., the ion source stage IS2 is a conventional mass filter of ions, such as a quadrupole or hexapole ion guide operated as a high-pass or band-pass filter, and the ion source stage IS3 is any of the previously mentioned types of mass analyzers. In this embodiment, the ion source stage IS2 is controlled in a conventional manner to preselect ions having desired molecular characteristics for analysis by a downstream mass analyzer and pass only such preselected ions to the mass analyzer, where the ions analyzed by the ELIT array 14, 205, 302 are the preselected ions separated by the mass analyzer according to their mass-to-charge ratio. The preselected ions exiting the ion filter may be, for example, ions having a particular ion mass or mass-to-charge ratio, ions having a mass or mass-to-charge ratio of an ion greater than and / or less than a particular ion mass or mass-to-charge ratio, ions having a mass or mass-to-charge ratio of an ion within a particular range of ion mass or mass-to-charge ratios, etc. In some alternative embodiments of this example, ion source stage IS2 may be a mass analyzer and ion source stage IS3 may be an ion filter, which may be operable as previously described to preselect ions having desired molecular characteristics exiting the mass analyzer for analysis by the downstream ELIT array 14, 205, 302. In other alternative embodiments of this example, ion source stage IS2 may be an ion filter and ion source stage IS3 may include a mass analyzer followed by another ion filter, where each of these ion filters operates as previously described.

[0050]

[0069] As another specific implementation of the ion isolation device 60 illustrated in Figure 5A, which should not be considered limiting in any way, the ion source 12 includes, by way of example, two stages and the ion treatment device 70 is omitted. In this exemplary implementation, the ion source stage IS1 is a conventional source of ions, e.g., electrospray, MALDI, etc., and the ion source stage IS2 is any of the conventional mass analyzers of the types previously described. This is the implementation previously described with respect to Figure 1, where the ELIT array 14, 205, 302 is operable to analyze ions exiting the mass analyzer.

[0051]

[0070] As yet another specific implementation of the ion separation device 60 illustrated in FIG. 5A, which should not be considered limiting in any way, the ion source 12 includes, by way of example, two stages and the ion treatment device 70 is omitted. In this example implementation, the ion source stage IS1 is a conventional source of ions, e.g., electrospray, MALDI, etc., and the ion source stage IS2 is a conventional single or multi-stage ion mobility spectrometer. In this embodiment, the ion mobility spectrometer is operable to separate ions generated in the ion source stage IS1 over time according to one or more functions of ion mobility, and the ELIT array 14, 205, 302 is operable to analyze the ions exiting the ion mobility spectrometer. In an alternative embodiment of this example, the ion source 12 can include only one stage IS1 in the form of a conventional source of ions, and the ion treatment device 70 can include a conventional single or multi-stage ion mobility spectrometer as one stage OS1 (or stage OS1 of the multi-stage device 70). In this alternative embodiment, the ELIT array 14, 205, 302 is operable to analyze ions generated in the ion source stage IS1, and the ion mobility spectrometer OS1 is operable to separate ions exiting the ELIT array 14, 205, 302 over time according to one or more functions of ion mobility. As another alternative embodiment of this example, a single or multiple stage ion mobility spectrometer can follow both the ion source stage IS1 and the ELIT array 14, 205, 302. In this alternative embodiment, an ion mobility spectrometer following the ion source stage IS1 is operable to separate ions generated in the ion source stage IS1 over time according to one or more functions of ion mobility, the ELIT array 14, 205, 302 is operable to analyze ions exiting the ion mobility spectrometer of the ion source stage, and an ion mobility spectrometer of the ion processing stage OS1 following the ELIT array 14, 205, 302 is operable to separate ions exiting the ELIT array 14, 205, 302 over time according to one or more functions of ion mobility.In any implementation of the embodiments described in this paragraph, further variations can include a mass analyzer operatively disposed upstream and / or downstream of the single or multi-stage ion mobility spectrometer in the ion source 12 and / or ion processing device 210.

[0052]

[0071] As yet another specific implementation of the ion separation device 60 illustrated in FIG. 5A, which should not be considered limiting in any way, the ion source 12 includes, by way of example, two stages, and the ion processing device 70 is omitted. In this example implementation, the ion source stage IS1 can be a conventional liquid chromatograph, such as, for example, an HPLC configured to separate molecules in a liquid according to molecular retention time, and the ion source stage IS2 can be a conventional source of ions, such as, for example, an electrospray. In this implementation, the liquid chromatograph is operable to separate molecular components in the liquid, the ion source stage IS2 is operable to generate ions from the liquid stream exiting the liquid chromatograph, and the ELIT array 14, 205, 302 is operable to analyze the ions generated by the ion source stage IS2. In an alternative embodiment of this example, the ion source stage IS1 can instead be a conventional size exclusion chromatograph (SEC) operable to separate molecules in the liquid by size. In another alternative embodiment, ion source stage IS1 may include a conventional liquid chromatograph followed by conventional SEC, or vice versa. In this implementation, ions are generated by ion source stage IS2 from a liquid that is separated twice, first according to molecular retention time and then subsequently according to molecular size, or vice versa. In any implementation of the embodiments described in this paragraph, a further variation may include a mass analyzer operably disposed between ion source stage IS2 and the ELIT array 14, 205, 302.

[0053]

[0072] Referring to FIG. 5B, a simplified block diagram of another embodiment of an ion separation apparatus 80 is shown, which includes, by way of example, a multi-stage mass analyzer apparatus 82, which may also include any of the ion mass detection systems 10, 200, 300 illustrated and described herein, i.e., CDMS, implemented as a high ion mass analysis component. In the illustrated embodiment, the multi-stage mass analyzer apparatus 82 includes an ion source (IS) 12 as illustrated and described herein, followed by a first conventional mass analyzer (MS1) 84 coupled thereto, followed by a conventional ion dissociation stage (ID) 86 coupled thereto and operative to dissociate ions exiting the mass analyzer, e.g., by one or more of collision induced dissociation (CID), surface induced dissociation (SID), electron capture dissociation (ECD), and / or photoinduced dissociation (PID), followed by a second conventional mass analyzer (MS2) 88 coupled thereto, followed by a conventional ion detector (D) 90, such as a microchannel plate detector or other conventional ion detector. The ion mass detection system 10 , 200 , 300 , ie, CDMS, is coupled in parallel with the ion dissociation stage 86 such that the ion mass detection system 10 , 200 , 300 , ie, CDMS, can selectively receive ions from the mass analyzer 84 and / or the ion dissociation stage 86 .

[0054]

[0073] MS / MS, for example using only an ion separator 82, is an established technique where precursor ions of a particular molecular weight are selected by a first mass analyzer 84 (MS1) based on their m / z value. The mass-selected precursor ions are fragmented in an ion dissociation stage 86, for example by collision-induced dissociation, surface-induced dissociation, electron capture dissociation, or photoinduced dissociation. The fragmented ions are then analyzed by a second mass analyzer 86 (MS2). Only the m / z values ​​of the precursor fragmented ions are measured in both MS1 and MS2. For high mass ions, the charge state is not resolved and therefore it is not possible to select precursor ions with a particular molecular weight based on m / z value alone. However, by coupling the device 82 to a CDMS 10, 200, 300 as illustrated and described herein, it is possible to select a narrow range of m / z values ​​and then use the CDMS 10, 200, 300 to determine the mass of the m / z-selected precursor ions. The mass analyzers 84, 88 can be, for example, one or any combination of a magnetic sector mass analyzer, a time-of-flight mass analyzer, and a quadrupole mass analyzer, although other types of mass analyzers can be used in alternative embodiments. In either case, m / z selected precursor ions of known mass leaving MS1 can be fragmented in ion dissociation stage 86, and the resulting fragmented ions can then be analyzed by MS2 (where only the m / z ratio is measured) and / or CDMS devices 10, 200, 300 (where the m / z ratio and charge are measured simultaneously). Thus, low mass fragments can be analyzed by conventional MS and high mass fragments (where the charge state is not resolved) are analyzed by CDMS.

[0055]

[0074] 6, an ion mass detection system 200 is shown that includes another embodiment of an electrostatic linear ion trap (ELIT) array 205 with associated control and measurement components. In the illustrated embodiment, the ELIT array 205 includes three individual ELITs 202, 204, 206, each configured similarly to the ELIT or ELIT region E3 of the ELIT array 14 illustrated in FIG. 1. For example, the ELIT 202 includes a charge detection cylinder CD1 surrounded by a ground chamber GC1, one end of which defines one of the mirror electrodes of one ion mirror M1, and an opposite end of which defines one of the mirror electrodes of another ion mirror M2, the ion mirrors M1, M2 being disposed at opposite ends of the charge detection cylinder 202. The ion mirror M1 is, for example, identical in structure and function to each of the ion mirrors M1-M3 illustrated in FIG. 1-2B, and the ion mirror M2 is, for example, identical in structure and function to the ion mirror M4 illustrated in FIG. 1-2B. A voltage source V1, for example, identical in structure and function to the voltage source V1 illustrated in FIG. 1-2B, is operably coupled to the ion mirror M1, and another voltage source V2, for example, identical in structure and function to the voltage source V4 illustrated in FIG. 1-2B, is operably coupled to the ion mirror M2. The ion mirror M1 defines an ion intake aperture AI1, for example, identical in structure and function to the aperture A1 of the ion mirror MX illustrated in FIG. 2A, and the ion mirror M2 defines an ejection aperture AO1, for example, identical in structure and operation to the aperture CA of the ion mirror M4 previously described with respect to FIG. 1 and FIG. 2B. A longitudinal axis 241 extends through the center of the ELIT 202 and, for example, bisects the apertures AI1 and AO1. The charge preamplifier CP1 is electrically coupled to the charge detection cylinder CD1 and is illustratively identical in structure and function to the charge preamplifier CP1 illustrated in FIG. 1 and previously described.

[0056]

[0075] ELIT204 is, by way of example, the same as ELIT202 described herein, with ion mirrors M3, M4 corresponding to ion mirrors M1, M2 of ELIT202, voltage sources V3, V4 corresponding to voltage sources V1, V2 of ELIT202, and intake / emission apertures AI2 / AO2 defining a longitudinal axis 242 that extends through ELIT204 and, by way of example, bisects apertures AI2, AO2. Charge amplifier CP2 is electrically coupled to charge detection cylinder CD2 of ELIT204 and, by way of example, is the same in structure and function as charge preamplifier CP2 illustrated in FIG.

[0057]

[0076] ELIT206 is similarly, by way of example, identical to ELIT202 described herein, with ion mirrors M5, M6 corresponding to ion mirrors M1, M2 of ELIT202, voltage sources V5, V6 corresponding to voltage sources V1, V2 of ELIT202, and intake / emission aperture AI3 / AO3 defining a longitudinal axis 243 that extends through ELIT206 and, by way of example, bisects apertures AI3, AO3. Charge amplifier CP3 is electrically coupled to charge detection cylinder CD3 of ELIT206 and, by way of example, is identical in structure and function to charge preamplifier CP3 illustrated in FIG.

[0058]

[0077] The voltage sources V1-V6 and the charge preamplifiers CP1-CP3 are operatively coupled to a processor 210 including a memory 212 as described with respect to FIG. 1, illustratively storing instructions which, when executed by the processor 210, cause the processor 210 to control the operation of the voltage sources V1-V6 to control the ion mirrors M1-M6 between the ion transmission and ion reflection modes previously described. Alternatively, one or more of the voltage sources V1-V6 may be programmable to operate as described above. In any case, the instructions stored in the memory 212 illustratively include further instructions which, when executed by the processor 210, cause the processor 210 to receive, process and record (store) charge signals detected by the charge preamplifiers CP1-CP3, and to process the recorded charge signal information to calculate the masses of ions trapped in each of the ELITs 202, 204, 206, as previously described. By way of example, the processor 210 is coupled to one or more peripheral devices 214, which may be the same as the one or more peripheral devices 20 previously described with respect to FIG.

[0059]

[0078] 6 illustrates an embodiment of an ion steering array 208 operatively coupled between the ion source 12 and the ion intake apertures AI1-AI3 of each of the ELITs 202, 204, 206 of the ELIT array 205. The ion source 12, as described with respect to FIGS. 1 and / or 5, is configured to generate and deliver ions to the ion steering array 208 via the ion aperture IA. An ion steering voltage source V ST is operatively coupled between the processor 210 and the ion steering array 208. As will be described in more detail below, the processor 210 illustratively controls an ion steering voltage source V ST, thereby causing the ion steering array 208 to selectively steer and guide ions exiting from the ion aperture IA of the ion source 12 through respective intake apertures AI1-AI3 into the ELITs 202, 204, 206. The processor 210 is further configured, i.e., programmed, to control the voltage sources V1-V6, thereby causing the ion mirrors M1-M6 of the ELITs 202, 204, 206 to selectively switch between an ion transmission mode and an ion reflection mode, thereby trapping at least one ion in each of the ELITs 202, 204, 206, and then oscillating such ions back and forth through respective charge detection cylinders CD1-CD3 between the ion mirrors M1 / M2, M3 / M4, and M5 / M6 of the ELITs 202, 204, 206, respectively, and measuring and recording ion charge detection events detected by respective charge preamplifiers CP1-CP3 as previously described.

[0060]

[0079] The ion steering array 208 illustratively includes three sets of four conductive pads P1-P4, P5-P8, and P9-P12 disposed on each of two separate planar substrates such that each of the conductive pads P1-P12 on one of the substrates is aligned opposite each of the conductive pads on the other substrate. In the embodiment illustrated in FIG. 6, only one of the substrates 220 is shown.

[0061]

[0080] 7A-7C, a portion of the ion steering array 208 is shown and its control and operation are illustrated to selectively steer ions to a desired location. As shown in the examples of FIGS. 7B and 7C, the voltages DC1-DC4 of the example portion of the ion steering array 208 are controlled to cause ions exiting the ion aperture IA of the ion source 12 in the direction indicated by arrow A to be redirected approximately 90 degrees to be directed along a path aligned, i.e., collinear, with the ion intake aperture AI1 of the ELIT 202. Although not illustrated in the figures, any number of conventional planar ion carpets and / or other conventional ion focusing structures may be used to focus ion trajectories exiting the ion aperture IA of the ion source and / or to align ion trajectories selectively altered by the ion steering array 208 with the ion intake apertures AI1-AI3 of the ELITs 202, 204, 206, respectively.

[0062]

[0081] 7A, a pattern of four substantially identical, spaced apart conductive pads P11-P41 is formed on an inner major surface 220A of one substrate 220, which also has an opposite outer major surface 220B, and a substantially identical pattern of four substantially identical, spaced apart conductive pads P12-P42 is formed on an inner major surface 222A of another substrate 222, which also has an opposite outer major surface 222B. The inner surfaces 220A, 222A of the substrates 220, 222 are spaced apart in a generally parallel relationship, with the conductive pads P11-P41 juxtaposed over each one of the conductive pads P12-P42. The inner major surfaces 220A, 222A of the spaced apart substrates 220, 222 are illustratively spaced apart by a distance D therebetween. P In one embodiment, the width of the channel 225 is D P is about 5 cm, but in other embodiments the distance D P In either case, the substrates 220, 222 together form an exemplary portion of the ion steering array 208.

[0063]

[0082] The opposing pad pairs P31, P32 and P41, P42 are upstream of the opposing pad pairs P11, P12 and P21, P22, which in turn are downstream of the opposing pad pairs P41, P42 and P31, P32. In this regard, the "direction of unaltered ion movement" through the channel 225, as that term is used herein, is "upstream," and is generally parallel to the direction A of ions exiting the ion source 12. The lateral edges 220C, 222C of the substrates 220, 222 are aligned, as are the opposing lateral edges 220D, 222D, and the "changed direction of ion migration," as that term is used herein, is from the aligned edges 220C, 222C toward the aligned edges 220D, 222D, and is generally perpendicular to such aligned edges 220C, 222C and 220D, 222D.

[0064]

[0083] In the embodiment illustrated in FIG. 6, an ion steering voltage source V ST is illustratively configured to generate at least 12 switchable DC voltages, each voltage operatively connected to a respective pair of opposing conductive pads P1-P12. Four of the 12 DC voltages, DC1-DC4, are illustrated in FIG. 7A. A first DC voltage DC1 is electrically connected to each of the juxtaposed conductive pads P11, P12, a second DC voltage DC2 is electrically connected to each of the juxtaposed conductive pads P21, P22, a third DC voltage DC3 is electrically connected to each of the juxtaposed conductive pads P31, P32, and a fourth DC voltage DC4 is electrically connected to each of the juxtaposed conductive pads P41, P42. In the illustrated embodiment, each of the DC voltages DC1-DC12 is controlled by, for example, a power supply, via the processor 210 and / or a voltage source V STAlthough the voltages DC1-DC12 are individually controlled via programming, in other embodiments, two or more of the DC voltages DC1-DC12 may be controlled as a group. In any event, although the voltages DC1-DC12 are illustrated and disclosed as DC voltages, this disclosure contemplates other embodiments, in which the voltage sources V ST may alternatively or additionally be configured to generate any number of AC voltages, such as, for example, one or more RF voltages, and supply any one or more such AC voltages to corresponding ones or pairs of conductive pads and / or to one or more ion carpets or other ion focusing structures, in embodiments including these.

[0065]

[0084] 7B and 7C, the operation of the ion steering channel array 208 illustrated in FIG. 6 will be described using the four opposing conductive pad pairs P11 / P12, P21 / P22, P31 / P32, and P41 / P42 of FIG. 7A and 7B as examples. It will be understood that the four conductive pads P5-P8 and the four conductive pads P9-P12 illustrated on the substrate 220 of FIG. 6 similarly constitute opposing aligned and juxtaposed conductive pad pairs disposed on the respective inner surfaces 220A, 222A of the substrates 220, 222, and that each such set of four opposing pairs of conductive pads is coupled to a voltage source V ST It will be appreciated that each of the inputs can be controlled by respective switchable DC (and / or AC) voltages DC5-DC12 produced by a voltage source V. In any case, for clarity of illustration, the DC voltages DC1-DC4 have been omitted from FIGS. 7B and 7C, and instead, the voltage sources V ST 7B, an example portion of the ion steering array 208 is shown graphically illustrating the DC voltages DC1-DC4 applied to the connected conductive pad pairs P11 / P12, P21 / P22, P31 / P32, and P41 / P42 produced by the reference voltage V REF is applied to each of the conductive pad pairs P11 / P12 and P21 / P22, and V REFA smaller potential −XV is shown applied to each of the conductive pad pairs P31 / P32 and P41 / P42. REF can be positive or negative or zero voltage, e.g., ground potential, and -XV is V REF This can be any voltage, lesser positive, negative, or zero voltage, and is configured to establish an electric field E1 as shown in FIG. 7B, which is parallel to sides 220C / 222C and 220D / 222D of substrates 220, 222 and extends in the direction of unaltered ion migration, i.e., from downstream conductive pad pairs P11 / P12, P21 / P22 toward upstream conductive pad pairs P31 / P32 and P41 / P42. With electric field E1 established as illustrated in FIG 7B, ion A exiting ion source 12 through ion aperture IA enters channel 225 between downstream conductive pad pairs P11 / P12, P21 / P22 and is steered or guided (or directed) by electric field E1 along a direction of unaltered ion movement 230, which is the same direction as electric field E1 and aligned, i.e., collinear, with ion aperture IA of ion source 12. Such ion A is guided through channel 225 along its unaltered direction of movement, as illustrated in FIG 7B, for example.

[0066]

[0085] Now referring specifically to FIG. 7C, if it is desired to change the direction of ion A from the unaltered direction of ion movement shown in FIG. 7B to the altered direction of ion movement, voltage source V ST The DC voltages DC1 and DC3 generated by the REF is applied to each of the conductive pad pairs P21 / P22 and P31 / P32, and V REFA smaller potential −XV is applied to each of the conductive pad pairs P11 / P12 and P41 / P42, such that an electric field E2 is established as shown in FIG 7C, where the electric field E2 is perpendicular to the sides 220C / 222C and 220D / 222D of the substrates 220, 222 and extends in the unaltered direction of ion movement, i.e., from the sides 220C / 222C of the substrates 220, 222 toward the sides 220D / 222D of the substrates 220, 222. With the electric field E2 established as illustrated in FIG 7C, ions A exiting the ion source 12 through the ion aperture IA are steered or guided (or directed) by the electric field E2 along the altered direction of ion movement 240, which is in the same direction as the electric field E2 and aligned, i.e., collinear, with the ion aperture IA of the ion source 12. Such ions A are guided through channel 225 along an unaltered direction of travel between conductive pad pairs P11 / P12, P41 / P42, as shown, for example, in Figure 7C. In some embodiments, one or more conventional ion carpets and / or other conventional ion focusing structures can be used to confine the ions along ion trajectories 240 illustrated in Figure 7C.

[0067]

[0086] 6, the instructions stored in memory 212, when executed by processor 210, may, by way of example, cause processor 210 to control ion steering voltage source V to selectively generate and switch voltages DC1-DC12 as previously described with respect to FIGS. 1-4B when processor 210 records respective ion charge detection information in memory 212. STto guide ions along the ion steering array 208 and subsequently transmit at least one ion to a respective ion intake aperture AI1-AI3 of each ELIT 202, 204, 206, and to control the voltage sources V1-V6 to selectively generate and switch the DC voltages produced thereby to control each ion mirror M1-M6 between its ion transmission mode and ion reflection mode to trap at least one ion guided by the ion steering array 208 into each ELIT 202, 204, 206, and then cause each trapped ion(s) to oscillate back and forth between the respective ion mirrors M1-M6 of each ELIT 202, 204, 206. With the aid of Figures 8A-8F, an example of such a process will be described as operating on one or more positively charged ions, although it will be understood that the process 100 may alternatively operate on one or more negatively charged ions. In the following description, references to a particular one or more of the conductive pads P1-P12 will be understood to refer to pairs of opposing, juxtaposed, and spaced apart conductive pads disposed on the inner surfaces 220A, 222A of the respective substrates 220, 222 shown in the example with respect to Figure 7A, and references to a voltage applied to a particular one or more of the conductive pads P1-P12 will be understood to be applied to each such pair of opposing, juxtaposed, and spaced apart conductive pads shown in the example with respect to Figures 7B and 7C. Furthermore, the DC voltage V REF can be any positive or negative voltage, or zero voltage, e.g., ground potential, and as illustrated in Figures 8A-8F, -XV is V REF 7B and 7C, this electric field is V. The voltage V can be any voltage less than V, positive, negative, or zero voltage, so as to establish a corresponding electric field within the channel 225 as shown in FIG. REF It will be appreciated that the conductive pads 100 and 102 extend in a direction from the conductive pads 100 controlled at -XV to the conductive pads 102 controlled at -XV.

[0068]

[0087] Referring to FIG. 8A, the processor 210 controls a voltage source V ST By controlling the voltage V REF to each of the pads P1-P4. ST is connected to each of the pads P9-P12 as shown in Figure 8A. REF In another implementation, V ST can be controlled to apply -XV to each of pads P9-P12. In either case, the resulting electric field within channels 225 of ion steering array 208 as a result of applying such voltages pulls ions through channels 225 and out ion aperture IA of ion source 12 in a direction of unaltered ion movement along illustrated ion trajectory 250.

[0069]

[0088] Referring to FIG. 8B, the processor 210 then controls the voltage source V STto switch the voltages applied to pads P2 and P4 to -XV, while otherwise maintaining the voltages previously applied at P1, P3, and P5-P12. The electric field established in channels 225 of ion steering array 208 as a result of application of such switched voltages steers ions that were previously traveling from ion source 12 in an unaltered direction of ion travel along ion trajectory 250 illustrated in FIG. 8A toward ion intake aperture AI1 of M1 of ELIT 202 in an altered direction of ion travel along ion trajectory 252. Simultaneously with, or prior to, or after this switching, processor 210 is operable to control voltage sources V1 and V2 to produce voltages that cause both ion mirrors M1 and M2 to operate in their ion transmission modes, e.g., as described with respect to FIGS. 1-2B. As a result, ions traveling along ion trajectories 252 through the channels 225 of the ion steering array 208 are directed into the intake aperture AI1 of the ELIT 202 through M1, and are transmitted through M1, through the charge detection cylinder CD1, and through M2 by the ion transmission fields established in each of the ion mirrors M1 and M2, as illustrated by the ion trajectory 252 shown in FIG. 8B. In some embodiments, one or more conventional ion carpets and / or other conventional ion focusing structures may be operatively disposed between the ion steering array 208 and the ion mirror M1 of the ELIT 202 to direct ions traveling along ion trajectories 252 into the ion intake aperture AI1 of the ELIT 202. In any case, the processor 210 is operable at some subsequent point to control V2 to produce a voltage that causes the ion mirror M2 to switch from an ion transmission mode of operation to an ion reflection mode of operation to reflect ions back towards M1, e.g., as described with respect to FIGS. 1-2B. The timing of this switching of M2 depends, for example, on whether operation of ELIT 202 is controlled by processor 210 in the random trapping mode described with respect to FIG. 3 or in the triggered trapping mode.

[0070]

[0089] 8C, the processor 210 is then operable to control the voltage source V1 to generate a voltage that switches the ion mirror M1 from an ion transmission mode to an ion reflection mode of operation. The timing of this switching of M1 depends, by way of example, on whether the operation of the ELIT 202 is controlled by the processor 210 in the random trapping mode described with respect to FIG. 3 or in the triggered trapping mode, but in either case, the switching of M1 to the ion reflection mode traps at least one ion within the ELIT 202, as illustrated by the ion trajectory 252 shown in FIG. 8C. When at least one such ion is trapped within the ELIT 202 and both M1 and M2 are controlled by voltage sources V1 and V2, respectively, to operate in their ion reflecting modes, as previously described with respect to FIG. 3, the ion (one or more) trapped within the ELIT 202 oscillates back and forth between the ion mirrors M1 and M2, passing through the charge detection cylinder CD1 and inducing a corresponding charge thereon, which is detected by the charge preamplifier CP1 and recorded by the processor 210 in memory 212.

[0071]

[0090] Concurrently with or subsequent to the aforementioned control of the ELIT 202, and as the ions (one or more) oscillate back and forth between the ion mirrors M1, M2 within the ELIT 202, the processor 210 controls V ST 8C, the voltage applied to the pads P2 and P4 is controlled to V REF and change the voltage applied to pads P5-P8 from -XV to V REF and the voltage applied to pads P9-P12 is V REF The electric field resulting in the application of such a voltage in the channel 225 of the ion steering array 208 again pulls ions exiting the ion aperture IA of the ion source 12 through the channel 225 in a direction of unaltered ion travel along an exemplary ion trajectory 250.

[0072]

[0091] 8D, the processor 210 then controls the voltage source V STto switch the voltages applied to pads P6 and P8 to −XV, while otherwise maintaining the voltages previously applied at P1-P4, P5, P7, and P9-P12. The electric field established within channels 225 of ion steering array 208 as a result of application of such switched voltages steers ions that were previously traveling from ion source 12 in an unaltered direction of ion travel along ion trajectory 250 illustrated in FIG. 8C toward ion intake aperture AI2 of M2 of ELIT 204 along an altered direction of ion travel along ion trajectory 254. Simultaneously with, before, or after this switching, processor 210 is operable to control voltage sources V3 and V4 to produce voltages that cause both ion mirrors M3 and M4 to operate in their ion transmission modes. As a result, ions traveling along ion trajectories 254 through the channels 225 of the ion steering array 208 are directed into the intake aperture AI2 of the ELIT 204 through M3 and are transmitted through M3, through the charge detection cylinder CD2, and through M4 by the ion transmission fields established in each of the ion mirrors M3 and M4, as illustrated by the ion trajectory 254 shown in FIG. 8D. In some embodiments, one or more conventional ion carpets and / or other conventional ion focusing structures may be operatively disposed between the ion steering array 208 and the ion mirror M3 of the ELIT 204 to direct ions traveling along ion trajectories 254 into the ion intake aperture AI2 of the ELIT 204. In any case, the processor 210 is operable at some subsequent point to control V4 to generate a voltage that causes the ion mirror M4 to switch from an ion transmission mode of operation to an ion reflection mode of operation to reflect ions back towards M3. The timing of this switching of M4 depends, for example, on whether operation of ELIT 204 is controlled by processor 210 in the random trapping mode described with respect to FIG. 3 or in the triggered trapping mode.

[0073]

[0092] Following the operating state illustrated in Figure 8D, the processor 210 is operable to control voltage source V3 to produce a voltage that switches ion mirror M3 from an ion transmission mode to an ion reflection mode of operation, similar to that described with respect to Figure 8C. The timing of this switching of M3 depends, by way of example, on whether operation of the ELIT 204 is controlled by processor 210 in the random trapping mode described with respect to Figure 3 or in the triggered trapping mode, but in any case, the switching of M3 to the ion reflection mode traps at least one ion within the ELIT 204, as illustrated by ion trajectory 254 shown in Figure 8E. When at least one such ion is trapped within the ELIT 204 and both M3 and M4 are controlled by voltage sources V3 and V4, respectively, to operate in their ion reflecting modes, as previously described with respect to Figure 3, the ion(s) trapped within the ELIT 204 oscillates back and forth between the ion mirrors M3 and M4, passing the charge detection cylinder CD2 and inducing a corresponding charge thereto which is detected by the charge preamplifier CP2 and recorded by the processor 210 in memory 212. In the operational condition illustrated in Figure 8E, the ion moves back and forth simultaneously within each of the ELITs 202 and 204, and the ion charge / timing measurements taken from each of the charge preamplifiers CP1 and CP2 are therefore collected and stored simultaneously by the processor 210.

[0074]

[0093] Concurrently with or subsequent to the control of the ELIT 204 described above with respect to FIG. 8E, and with ions (one or more) oscillating simultaneously within each of the ELITs 202 and 204, the processor 210 ST By controlling the voltage applied to pads P6 and P8, REF8C. The electric field resulting in the application of such voltages in the channels 225 of the ion steering array 208 again pulls ions exiting the ion aperture IA of the ion source 12 through the channels 225 in a direction of unaltered ion movement along the example ion trajectory 250, as illustrated in FIG. 8C. The processor 210 then switches the voltage source V ST By controlling the voltage applied to pads P9 and P11, REF 8C , and otherwise maintains the voltages previously applied at P1-P8, P5, and P11-P12. The electric field established within the channels 225 of the ion steering array 208 as a result of applying such switched voltages steers ions that were previously traveling from the ion source 12 in an unaltered direction of ion travel along the ion trajectory 250 illustrated in FIG. 8C toward the ion intake aperture AI3 of M5 of the ELIT 206 along an altered direction of ion travel along the ion trajectory 256. Simultaneously with, or prior to, or after this switching, the processor 210 is operable to control voltage sources V5 and V6 to produce voltages that cause both ion mirrors M5 and M6 to operate in their ion transmission modes. As a result, ions traveling along ion trajectory 253 through channel 225 of ion steering array 208 are directed into the intake aperture AI3 of ELIT 206 through M5 and are transmitted through M5, through charge detection cylinder CD3, and through M6 by the ion transmission fields established in ion mirrors M5 and M6, respectively, as illustrated by ion trajectory 256 shown in Figure 8E. In some embodiments, one or more conventional ion carpets and / or other conventional ion focusing structures may be operatively disposed between the ion steering array 208 and ion mirror M5 of the ELIT 206 to direct ions traveling along ion trajectory 256 into the ion intake aperture AI3 of the ELIT 206.

[0075]

[0094] In either case, at some point thereafter, processor 210 is operable to control V6 to generate a voltage that causes ion mirror M6 to switch from an ion transmission mode of operation to an ion reflection mode of operation to reflect ions back towards M5. The timing of this switching of M6 depends, by way of example, on whether operation of ELIT 206 is being controlled by processor 210 in the random trapping mode or the triggered trapping mode described with respect to Figure 3. Processor 210 is then operable to control voltage source V5 to generate a voltage that causes ion mirror M5 to switch from an ion transmission mode to an ion reflection mode of operation, as described with respect to Figure 8C. The timing of this switching of M5 depends, by way of example, on whether the operation of ELIT 206 is controlled by processor 210 in the random trapping mode described with respect to Figure 3 or in the triggered trapping mode, but in either case, the switching of M5 to the ion reflection mode traps at least one ion in the ELIT 206, as illustrated by ion trajectory 256 shown in Figure 8F. Once at least one such ion is trapped in the ELIT 206 and both M5 and M6 are controlled by voltage sources V5 and V6, respectively, to operate in their ion reflection modes, as previously described with respect to Figure 3, the ion(s) trapped in the ELIT 206 oscillates back and forth between ion mirrors M5 and M6, passing through charge detection cylinder CD3 and inducing a corresponding charge thereto, which is detected by charge preamplifier CP3 and recorded by processor 210 in memory 212. In the operating condition illustrated in FIG. 8F, ions move back and forth simultaneously within each of the ELITs 202, 204, and 206, and ion charge / timing measurements taken from each of the charge preamplifiers CP1, CP2, and CP3 are therefore collected and stored simultaneously by the processor 210.

[0076]

[0095] Also, as illustrated in FIG. 8F, concurrently with or subsequent to the aforementioned control of the ELIT 206, and when ions (one or more) are oscillating simultaneously within each of the ELITs 202, 204, and 206, the processor 210 may ST , and switch the voltage applied to pads P5-P8 to -XV, and the voltage applied to pads P10 and P12 to V REF (or switch the voltages applied to pads P9 and P11 to -XV), such that pads P1-P12 are controlled to the voltages illustrated in (or described with respect to) FIGURE 8A. The electric field resulting in channel 225 of ion steering array 208 as a result of application of such voltages again pulls ions exiting ion aperture IA of ion source 12 through channel 225 in the direction of unaltered ion movement along exemplary ion trajectory 250, as illustrated in FIGURE 8A.

[0077]

[0096] For example, as described above with respect to step 126 of the process 100 illustrated in FIG. 3, after the ions have oscillated back and forth for a total ion cycle measurement time or total measurement cycle number in each of the ELITs 202, 204, and 206, the processor 210 is operable to control the voltage sources V1-V6 to switch each of the ion mirrors M1-M6 to an ion transmission mode such that ions trapped therein exit each of the ELITs 202, 204, and 206 via the ion ejection apertures AO1-AO2. Operation of the ion mass detection system 200 then returns, by way of example, to that described above with respect to FIG. 8B. At the same time, or at another convenient time, the collection of recorded ion charge / timing measurements are processed by the processor 210, for example, as described above with respect to step 140 of the process 100 illustrated in FIG. 3, to determine the masses of ions processed by each of the ELITs 202, 204, and 206.

[0078]

[0097] Depending on a number of factors, including, but not limited to, the dimensions of the ELITs 202, 204, 206, one or more frequencies of oscillation of the ions through each of the ELITs 202, 204, 206, and the total number of measurement cycles / total ion-cycle measurement time in each of the ELITs 202, 204, 206, the ions may oscillate back and forth simultaneously in at least two of the ELITs 202, 204, and 206, and the ion charge / timing measurements taken from each of the charge preamplifiers CP1, CP2, and CP3 may thus be collected and stored simultaneously by the processor 210. In the embodiment illustrated in FIG. 8F, for example, the ions oscillate back and forth simultaneously in at least two of the ELITs 202, 204, and 206, and the ion charge / timing measurements taken from each of the charge preamplifiers CP1, CP2, and CP3 may thus be collected and stored simultaneously by the processor 210. In another embodiment, the total measurement cycle number or total ion cycle measurement time of ELIT 202 may end before at least one ion is trapped in ELIT 206 as described above. In such a case, processor 210 may control voltage sources V1 and V2 to switch ion mirrors M1 and M2 to their transmission mode of operation, such that ion(s) oscillating therein exit through mirror M2 before at least one ion is caused to oscillate in ELIT 206. In such an embodiment, ions may not oscillate back and forth in all of ELITs 202, 204, and 206 simultaneously, but may oscillate back and forth in at least two of ELITs 202, 204, and 206 simultaneously at any one time.

[0079]

[0098] 9, an ion mass detection system 300 is shown that includes yet another embodiment of an electrostatic linear ion trap (ELIT) array 302 with associated control and measurement components. In the illustrated embodiment, the ELIT array 302 includes three individual ELITs E1-E3, each configured similarly to the ELITs 202, 204, 206 illustrated in FIG. 6. In the embodiment illustrated in FIG. 9, a voltage source V1, illustratively similar in structure and function to the voltage source V1 illustrated in FIG. 1-2B, is operably coupled to the ion mirror M1 of each of the ELITs E1-E3, and another voltage source V2, illustratively similar in structure and function to the voltage source V4 illustrated in FIG. 1-2B, is operably coupled to the ion mirror M2 of each of the ELITs E1-E3. In alternative embodiments, the ion mirrors M1 of two or more of the ELITs E1-E3 can be merged into one ion mirror, and / or the ion mirrors M2 of two or more of the ELITs E1-E3 can be merged into one ion mirror. In either case, the voltage sources V1, V2 are electrically coupled to the processor 304, and the three charge preamplifiers CP1-CP3 are electrically coupled between the processor 304 and the respective charge detection cylinders CD1-CD3 of each of the ELITs E1-E3. The memory 306 illustratively includes instructions that, when executed by the processor 304, cause the processor 304 to control the voltage sources V1 and V2 to control the operation of the ELITs E1-E3 as described below. As an example, the processor 304 is operatively coupled to one or more peripheral devices 308, which can be the same as the one or more peripheral devices 20 described above with respect to FIG. 1.

[0080]

[0099] The ion mass detection system 300 is similar in some respects to the ion mass detection system 200 in that the ion mass detection system 300 includes an ion source 12 operably coupled to an ion steering array 208, the structure and operation of which have been previously described. The instructions stored in the memory 306 illustratively further include instructions that, when executed by the processor 304, cause the processor 304 to control the ion steering array voltage supply V as previously described. ST is controlled.

[0081]

[0100] 9, the ion mass detection system 300 further includes, by way of example, three conventional ion traps IT1-IT3, each having a respective ion inlet TI1-TI3 and an opposing ion outlet TO1-TO3. Ion trap IT1 is, by way of example, positioned between the set of conductive pads P1-P4 and the ion mirror M1 of the ELIT E1, as shown in FIG. 9, such that a longitudinal axis 241 extending through the center of the ELIT E1 bisects the ion inlet TI1 and ion outlet TO1 of IT1 and passes through the center of the pad pairs P1 / P2 and P3 / P4. Similarly, ion trap IT2 is located between the set of conductive pads P5-P8 and the ion mirror M1 of ELIT E2, with a longitudinal axis 242 extending through the center of ELIT E2 that bisects the ion inlet TI2 and the ion outlet TO2 of IT2 and passes through the center between the pad pairs P5 / P6 and P7 / P8, and similarly, ion trap IT3 is located between the set of conductive pads P9-P12 and the ion mirror M1 of ELIT E3, with a longitudinal axis 243 extending through the center of ELIT E3 that bisects the ion inlet TI3 and the ion outlet TO3 of IT3 and passes through the center between the pad pairs P9 / P10 and P11 / P12. Each of ion traps IT1-IT3 can be any conventional ion trap, examples of which may include, but are not limited to, a conventional quadrupole ion trap, a conventional hexapole ion trap, etc.

[0082]

[0101] Ion trap voltage source V ITA voltage source V is operatively coupled between the processor 304 and each of the ion traps IT1-IT3. IT is configured to produce appropriate DC and AC, e.g., RF, voltages for isolating and individually controlling the operation of each of the ion traps IT1-IT3 in a conventional manner.

[0083]

[0102] The processor 304 may, for example, control the ion steering array voltage source V ST , which in turn steers one or more ions exiting the ion aperture IA of the ion source 12 into the ion inlets TI1-TI3 of each of the ion traps IT1-IT3, as described with respect to Figures 8A-8F. In some embodiments, one or more conventional ion carpets and / or other ion focusing structures may be disposed between the ion steering array 208 and one or more of the ion traps IT1-IT3 to direct ions from the ion steering array 208 into the ion inlets TI1-TI3 of each of the ion traps IT1-IT3. The processor 304 further controls the ion trap voltage supply V IT to produce corresponding control voltages for controlling the ion inlets TI1-TI3 of the ion traps IT1-IT3 to accept ions therein, and to conventionally control the ion traps IT1-IT3 to trap or confine ions therein.

[0084]

[0103] When ion traps IT1-IT3 are filled with ions, processor 304 can be configured, e.g., programmed, to control V1 and V2 to produce appropriate DC voltages that control ion mirrors M1 and M2 of ELITs E1-E2 to operate in their ion-transmitting modes of operation, thereby causing any ions contained therein to exit through ion outlets AO1-AO3, respectively. When at least one ion is trapped within each of ion traps IT1-IT3, via control of ion steering array 208 and ion traps IT1-IT3 as described herein, processor 304 can be configured, e.g., programmed, to control V2 to produce appropriate DC voltages that control ion mirror M2 of ELITs E1-E3 to operate in their ion-reflecting modes of operation. Processor 304 then controls ion trap voltage source V IT to produce appropriate voltages that cause the ion outlets TO1-TO3 of the respective ion traps IT1-IT3 to be simultaneously opened, thereby directing at least one ion trapped therein through the respective ion intake apertures AI1-AI3 of the respective ion mirror M1 to the respective one of the ELITs E1-E3. When the processor 304 determines that at least one ion has entered a respective ELIT E1-E3 after a period of time following the simultaneous opening of the ion traps IT1-IT3 or following detection of charge by each of the charge preamplifiers CP1-CP3, the processor 304 is operable to control the voltage source V1 to produce appropriate DC voltages that control the ion mirrors M1 of the ELTs E1-E3 to operate in their ion reflecting modes of operation, thereby trapping at least one ion in each of the ELITs E1-E3.

[0085]

[0104] When the ion mirrors M1 and M2 of each of the ELITs E1-E3 are operating in an ion-reflecting mode of operation, at least one ion in each of the ELITs E1-E3 oscillates back and forth simultaneously between M1 and M2, passing through a respective one of the charge detection cylinders CD1-CD3 each time. The corresponding charges induced in the charge detection cylinders CD1-CD3 are detected by the respective charge preamplifiers CP1-CP3, and the charge detection signals produced by the charge preamplifiers CP1-CP3 are stored in memory 306 by the processor 304 and then processed by the processor 304, for example, as described with respect to step 140 of the process 100 illustrated in FIG. 3, to determine the mass of the ion processed by the respective one of the ELITs E1-E3.

[0086]

[0105] Although embodiments of ion mass detection systems 200 and 300 are illustrated in Figures 6-8F and 9, respectively, as including three ELITs, it will be understood that one or both of such systems 200, 300 can alternatively include a fewer number of ELITs, e.g., two, or a greater number, e.g., four or more, of ELITs. Control and operation of the various components in any such alternative embodiments will generally follow the concepts described above, and one of ordinary skill in the art will recognize that any modifications of system 200 and / or system 300 necessary to implement any such embodiment(s) will relate to mechanical steps only. Furthermore, although embodiments of ion mass detection systems 200 and 300 are illustrated in Figures 6-8F and 9, respectively, as including an exemplary ion steering array 208, it will be understood that one or more other ion guiding structures can alternatively or additionally be used to steer or guide ions as described above, and any such alternative ion guiding structure(s) are intended to be within the scope of the present disclosure. As one non-limiting example, an array of DC quadrupole beam deflectors may be used in conjunction with one or both of systems 200, 300 to steer or guide ions as described above. In such embodiments, one or more focusing lenses and / or ion carpets may also be used to focus ions into the various ion traps as described above.

[0087]

[0106] 10, there is shown an embodiment of a charge detection mass analyzer apparatus 400 which represents a variation of the apparatus 300 illustrated in FIG. 9. In the apparatus 400 illustrated in FIG. 10, ions generated in an ion source region 402 are captured and stored by an ion trap 418 which is then controlled in a pulsed mode to selectively deliver ions stored therein to an ion mass and charge detector 434. Thus, the apparatus 400 is configurable and operable to capture and store generated ions in the ion trap 418 and then control the ion trap 418 in a pulsed manner to controllably deliver packets of time compressed ions to the ion mass and charge detector 434, for example in the form of a single stage electrostatic linear ion trap (ELIT) 434. In some embodiments, the ion outlet of the ion trap 418 can be spaced from the ion inlet of the detector 434 by a distance which allows ions traveling therebetween to be separated in time according to their mass to charge values. In such embodiments, ions having different mass-to-charge ratio windows or ranges can be trapped by varying the delay between the release of ions from the ion trap 418 and capture of the ions at the detector 434. In some embodiments, an ion filter 424 is disposed between the ion trap 418 and the detector 434, and in such embodiments the ion filter 424 is controllable to filter ions exiting the ion trap 418 according to their mass-to-charge ratio, so as to alternatively or additionally select or limit the mass-to-charge ratio or range of mass-to-charge ratios of ions delivered by the ion trap 418 to the detector 434.

[0088]

[0107] As briefly described above, the illustrated device 400 of FIG. 10 includes an ion source region 402 configured to generate ions and deliver the generated ions to an ion inlet of an ion trap 418. In an illustrated embodiment, the ion source region 402 includes an ion source 404 coupled to a source region 408 via a capillary 406. In some embodiments, the capillary 406 can be temperature controlled, e.g., heated and / or cooled. In either case, the source region 408 is operably coupled to a pump P1 that is operable to control the region 408 to a vacuum, such that the region 408 defines a first differentially pumped region. The ion source 404 is illustratively located outside the source region 404, e.g., atmospheric or other pressure, and configured to deliver ions from a sample to the ion source region 408 via the capillary 406. In some such embodiments, the ion source 404 is a conventional electrospray ion source (EIS). In such an embodiment, the ESI source 404 is operably coupled to an output V1 of the voltage source 450, with the voltage source 150 configured to produce a suitable DC or time-varying signal at V1 to control operation of the ESI source 404. In either case, the sample from which ions are generated by the ion source 404 is, by way of example, a biological material, although in other embodiments the sample can be or include a non-biological material.

[0089]

[0108] As mentioned above, in some embodiments where the ion source 404 is located outside the first differentially pumped region 408 and is operable to generate and deliver ions to the source region 408, the source region 408 can include, for example, an ion processing interface 410 configured to efficiently deliver ions having a wide mass distribution to the ion inlet of the ion trap 418. In some such embodiments, the interface 410 can include, for example, a drift tube 412 having an open end located near or spaced from the ion outlet end of the capillary 406 and an opposite end coupled to one end of a funnel region 414 that tapers from the end of the drift tube 412 to an ion outlet with a reduced cross section. An ion carpet 416 can be operably coupled to the ion outlet of the funnel region 414 and can define an ion passage therethrough that is coupled to the ion inlet of the ion trap 418. At least one output V2 of voltage source 450 is electrically coupled to interface 410 to provide K number of DC and / or time-varying voltage signals to interface 401 to control its operation, where K can be any positive integer. A central longitudinal axis A of device 400 illustratively passes through the centers of various ion inlets and outlets described herein and further below. In embodiments including this, interface 410 illustratively defines a virtual jet disrupter therein configured to disrupt gas jets generated by gas flow through capillary 406 into differentially pumped region 408, thereby thermalizing ions and concentrating ions into ion trap 418.Further details relating to the structure and operation of embodiments of interface 410 are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013274, filed January 11, 2019, and International Patent Application No. PCT / US2019 / 035379, filed June 4, 2019, both entitled “HYBRID ION FUNNEL-ION CARPET (FUNPET) ATMOSPHERIC PRESSURE INTERFACE FOR CHARGE DETECTION MASS SPECTROMETRY,” the disclosures of which are expressly incorporated herein by reference in their entireties.

[0090]

[0109] In some alternative embodiments, the source region 408 may not include the interface 410. In other alternative embodiments, the ion source 404 may be provided in the form of one or more other conventional ion sources, one or more of which may be disposed outside the source region 408 and / or one or more of which may be disposed inside the source region 408. In some such embodiments, the source region 408 may include the interface 410, while in other such embodiments, the interface 410 may be omitted.

[0091]

[0110] An ion inlet of the ion trap 418 is defined by a central aperture formed through a conductive plate, grid, or the like 420, which is, for example, electrically connected to an output V3 of the voltage source 450. An ion outlet of the ion trap 418 is spaced from the ion inlet along a central axis A, and is also, for example, defined by a central aperture formed through a conductive plate, grid, or the like 422, which is, for example, electrically connected to another output V5 of the voltage source 450. Another pump P2 is operably coupled to the ion trap 418 and is, for example, operable to pump the ion trap 418 to a pressure, for example, a high vacuum, lower than that of the source region 408, such that the ion trap 418 defines a second, differently pumped region. In some embodiments, P2 is configured or operable to control the ion trap 418 to a pressure of 10-100 mbar, although in other alternative embodiments, P2 may control the ion trap 418 to pressures outside this range. In some embodiments, a gas source GS may be operably coupled to the ion trap 418, and in such embodiments may be operable to supply a buffer or other gas to the interior of the ion trap 418. In some such embodiments, the gas is selected such that collisions of ions therewith reduce the ion energy. In one embodiment, the ion trap 418 is configured as a conventional hexapole ion trap, although in alternative embodiments, the ion trap 418 may have another conventional configuration, e.g., quadrupole, octapole, etc. In either case, the ion trap 418 typically includes a plurality of elongated conductive rods surrounding an axis A to which an output V4 of a voltage source 450 is operably coupled. By way of example, the output V4 is coupled to the rods such that each opposing set or pair of rods is out of phase with another opposing pair, and the output voltage V4 is, by way of example, a time-varying, e.g., radio frequency, voltage. In some embodiments, V4 may further include one or more DC voltages.

[0092]

[0111] The operation of the ion trap 418 is conventional in that the voltage sources V3 and V5 are controllable DC voltages that are controlled to allow ions to enter the trap 418 through the ion inlet, to be trapped therein, and to release ions through the ion outlet. For example, voltage V3 is controlled to a DC potential that illustratively sets the ion energy. In an embodiment that includes a gas source GS, the gas source GS provides a background gas with which ions entering the ion trap 418 collide to thermally equilibrate excess kinetic energy taken up by the ions from the gas flow from the source region 408 into the ion trap 418. The time-varying voltage V4 operates to confine ions radially, and voltage V5 is controlled to trap ions in the ion trap 418 and to release ions from the ion trap 418. For example, to allow ions to transmit through ion trap 418, V5 is typically controlled to a potential less than the potential of V4, and to collect and store, i.e., trap, ions, potential B5 is, for example, raised to a potential that does not allow ions to transmit through the ion outlet of ion trap 418.

[0093]

[0112] In some embodiments, as briefly described above, the device 400 can include a mass-to-charge ratio filter 424 having an ion inlet coupled or integrated with, for example, the ion outlet of the ion trap 418. The ion outlet is spaced from the ion inlet of the filter 424 along a central axis A and is defined, for example, by a central opening formed through a conductive plate, grid, or the like 426 electrically connected to a further output V7 of the voltage source 450. Another pump P3 is operably coupled to the filter 424 and operable, for example, to pump the filter 424 to a lower pressure, for example, a high vacuum, than that of the ion trap 418, such that the filter 424 defines a third, differentially pumped region. In some embodiments, a gas source GS can be operably coupled to the filter 424.

[0094]

[0113] The mass-to-charge ratio filter 424 is illustratively provided in the form of a conventional quadrupole mass-to-charge filter, although in alternative embodiments the filter 424 may be provided in the form of a hexapole, octapole, or other conventional configuration. In either case, the mass-to-charge ratio filter 424 typically includes a plurality of elongated conductive rods circumscribing an axis A to which an output V6 of a voltage source 450 is operatively coupled. By way of example, the output V6 is coupled to the rods such that each opposing set or pair of rods is out of phase with another opposing pair, and the output voltage V6 is illustratively a time-varying, e.g., radio frequency, voltage. In some embodiments, V6 may further include one or more DC voltages.

[0095]

[0114] In some embodiments, voltage V7 is set sufficiently lower than voltage V5 so that ions are transmitted through filter 424. In another embodiment, voltage V7 can be switched to V5 as well to operate filter 424 as a second ion trap. In any case in the embodiment where voltage V6 is time-varying only, e.g., RF only, mass-to-charge ratio filter 424 illustratively operates as a high-pass filter, allowing only ions above a selected mass-to-charge ratio value to pass through filter 424. The selected mass-to-charge ratio value is illustratively a function of the magnitude of time-varying voltage V6. In such an embodiment, mass-to-charge ratio filter 424 thus operates as a high mass-to-charge ratio filter, preselecting, i.e., passing, only ions having mass-to-charge ratios above a selected mass-to-charge ratio threshold. In some alternative embodiments, voltage V6 includes time-varying and DC components, and mass-to-charge ratio filter 424, by way of example, operates as a band-pass filter to allow only ions within a selected range of mass-to-charge ratios to pass through filter 424. The selected range of mass-to-charge ratios, by way of example, is a function of the magnitude of the time-varying and DC components. In such embodiments, mass-to-charge ratio filter 424 thus operates as a mass-to-charge ratio band-pass filter to pre-select, i.e., pass, only ions having mass-to-charge ratios that are within a selectable range of the ions' mass-to-charge ratios.

[0096]

[0115] In some alternative embodiments, the mass-to-charge ratio filter 424 may be located upstream of the ion trap 418. In such embodiments, the filter 424 may be controlled in any of the modes described herein to pass only ions having a mass-to-charge ratio within a specified range of mass-to-charge ratios into the ion trap 418. In some such embodiments, the mass-to-charge ratio filter 424 may be located upstream and downstream of the ion trap 418. In such embodiments, the mass-to-charge ratio filter 424 upstream of the ion trap 418 may be controlled, by way of example, to pass only ions having a mass-to-charge ratio within a selected range of mass-to-charge ratios, and the mass-to-charge ratio filter 424 downstream of the ion trap 418 may be controlled to pass only ions having a mass-to-charge ratio within a subset of said selected range of mass-to-charge ratios. Alternatively, the two mass-to-charge ratio filters 424 may be controlled to pass only ions having a mass-to-charge ratio within the same range of mass-to-charge ratios. In this latter embodiment, the upstream mass-to-charge ratio filter 424 can be controlled to pass only ions having mass-to-charge ratios within a selected range of mass-to-charge ratios into the trap 418, and a mass-to-charge ratio filter 424 downstream of the ion trap 418 can be used to allow ions exiting the ion trap 418 to be separated in time as they pass through it on their way to the detector 434.

[0097]

[0116] In some alternative embodiments, a conventional drift tube may be substituted or replaced by the mass-to-charge ratio filter 424. In some such embodiments, the axial passage defined through the drift tube may have a constant cross-sectional area. In some such embodiments, the drift tube may be configured and controlled using one or more voltages produced by the voltage source 450 to radially focus ions moving axially therethrough. In another embodiment, at least a portion of the drift tube proximate the ion outlet end of the drift tube may be funnel shaped, i.e., the cross-sectional area of ​​the axial passage decreases in a direction toward the ion outlet. In some embodiments, at least the funnel portion may be configured and controlled using one or more voltages produced by the voltage source 450 to radially focus ions moving axially therethrough, and in another embodiment, the entire drift tube may be configured and controlled using one or more voltages produced by the voltage source 450 to radially focus ions moving axially therethrough. In some such embodiments, the plate or grid 426 can be replaced by a conventional ion carpet defining a central aperture therethrough, which can be configured and controlled using one or more voltages produced by voltage source 450 to further focus the ions into and through the aperture to the next stage of device 400.

[0098]

[0117] The apparatus 400 further includes a fourth differentially pumped region 428 having an ion inlet coupled or integrated with the ion outlet of the mass-to-charge ratio filter 424. A fourth pump P4 is operatively coupled to the region 428 and configured to pump the region 428 to a pressure less than that of the filter 424. In an exemplary embodiment, the fourth differentially pumped region 428 includes an ion lens and deflector 430 followed by a conventional energy analyzer 432 electrically connected to a voltage output V8 of a voltage source 450. In one embodiment, the energy analyzer 432 is a dual hemispherical deflection energy analyzer (HDA) and configured to transmit a narrow band of ion energies centered around a nominal ion energy of 130 eV / z. In alternative embodiments, the energy analyzer 432 may be implemented in another conventional manner and / or configured to deliver ion energies centered around another ion energy value.

[0099]

[0118] The apparatus 400 further includes an ion mass and charge detector 434, which in this exemplary embodiment is provided in the form of a single stage electrostatic linear ion trap (ELIT). The ELIT configuration is generally one stage of the ELIT 14 illustrated in FIGS. 1-2B and described in detail above. For example, the ELIT 434 includes spaced end caps 436, 438, each of which represents, by way of example, opposing halves of an ion mirror MX illustrated in FIGS. 2A and 2B, between which a detection cylinder 440 is disposed. The ELIT 434 is operably coupled to a pump P5, which is configured and controlled to establish a pressure, e.g., a vacuum, within a fifth differentially pumped region defined by the ELIT chamber. In one embodiment, the pump P5 is driven at a pressure of about 10 -9Although pump P5 is controlled to establish a pressure of 1000 mbar within the ELIT 434, in alternative embodiments pump P5 can be controlled to establish higher or lower pressures within the ELIT chamber.

[0100]

[0119] An input of a conventional charge sensitive preamplifier 442 is electrically connected to the charge detection cylinder 440, and an output of the preamplifier 442 is electrically coupled to an input of a conventional processor 444. The processor 444 illustratively includes or is coupled to a memory 446, which stores instructions executable by the processor 444 to control the operation of the apparatus 444 as described below. In some embodiments, the processor 444 is operatively coupled to one or more peripheral devices PD 448 via P number of signal paths, where P can be any positive integer. In some embodiments, the processor 444 can also be electrically coupled to a voltage source 450 via M number of signal paths, where M can be any positive integer. In such embodiments, the processor 444 can be programmed to control the operation of the voltage source 450. In alternative embodiments, the voltage source 450 can itself be programmable and / or manually controllable. In either case, the charge sensitive preamplifier 442, processor 444, memory 446, and peripheral device(s) 448 are, by way of example, all as described above with respect to FIG.

[0101]

[0120] A voltage output V9 of the voltage source 450 is electrically connected to the ion mirror 436, and another voltage output V10 of the voltage source 450 is electrically connected to the ion mirror 438. It will be understood that each of the voltages V9 and V10 includes a number of different switchable voltages for controlling the operation of individual ones of the ion mirrors 436, 438, as shown by way of example in Figures 2A and 2B and described in detail above, and that the operation of the ELIT 434 under the control of such voltages V9 and V10 is also as described with respect to each of the stages depicted in Figures 1-4E.

[0102]

[0121] 10 and 11, pulsed operation of the CDMS device 400 involves selective control of at least voltages V5, V9, and V10. It will be appreciated that a high state of voltages V5, V9, and V10, which corresponds to an ion storage or trapping state in the case of V5 causing ions to be trapped and stored in the ion trap 418, i.e., a voltage of V5, which corresponds to an ion storage or trapping state in the case of the ion mirrors 436, 438, i.e., voltages of V9 and V10 which cause the ion mirrors 436, 438 to operate in their reflective mode to receive ions therein from the charge detection cylinder 440, reverses the direction of ion movement, causing the ions to accelerate back through the charge detection cylinder 440 and towards another mirror, causing the ions to be trapped in the ELIT 434 and oscillate back and forth between the ion mirrors 436, 438, each time passing the detection cylinder 440, as described above. The low states of voltages V5, V9, and V10 correspond to the transmission state, i.e., voltages at which ions are released and ejected from the ion trap 418, which, as described above, causes the ion mirrors 436, 438 to operate in their transmission mode, allowing ions to transmit through them.

[0103]

[0122] The ion source 404 generates ions in response to a voltage V1 produced by a voltage source 450. In some embodiments, the processor 444 is operable to execute instructions stored in the memory 446 to control the voltage V1 to cause the ion source 404 to generate ions. In alternative embodiments, the voltage source 450 can itself be programmed to do so, or the voltage source 450 can be manually controlled to produce V1. In either case, the generated ions pass through the source region 408 and into the ion trap 418. In embodiments in which the source region 408 includes an interface 410, the voltage source 450 is operable to produce one or more voltages V2 to control the interface 410 to pass ions therethrough, as briefly described above. In either case, the voltage V3 produced by the voltage source 450 controls the ion inlet of the ion trap 418 to set the energy of the ions entering from the source region 408 to a target energy, e.g., about 130 eV / z. Initially, as shown in FIG. 11, voltage (one or more) V5 is set to a trapping state to capture, trap, and store the generated ions in the ion trap 418, and voltages V9 and V10 are set to a transmitting state to clear the ELIT 434 by allowing any ions traveling towards it to pass through it.

[0104]

[0123] Pulsed operation of the device 400 begins with voltage(s) V5 switching to a transmission state for a pulse width period tw, after which voltage(s) V5 is switched back to a trapping state again. The pulse width period tw is selectable, i.e., adjustable, during which ions stored in the ion trap 418 are released or ejected therefrom in response to the electric field established by voltages V5 and V7 and travel into region 424 and towards the ELIT 434. In an embodiment in which region 424 includes a mass-to-charge ratio filter, only ions having a mass-to-charge ratio value selected for passage by voltage(s) V6 pass through region 424 into region 428. Ions with energies within a narrow band of energies about the transmission energy of the energy analyzer 432 pass through region 428 into the ion mirror 436 of the ELIT 434, and ions with energies outside this narrow band are deflected away from the ion entrance of the ELIT 434.

[0105]

[0124] A delay time t following the transition of voltage V5 (greater than or equal to 1) to the ion transmission state to release ions from the ion trap 418. D1 Upon expiration of the delay time t , the voltage V10 to the rear ion mirror or end cap 438 is switched from the transmitting state to the trapping or reflecting state. Ions entering the rear ion mirror or end cap 438 from the charge detection cylinder 440 are then reversed in direction by the ion reflecting electric field established therein, as described in detail above with respect to Figures 2A and 2B, and accelerated by the ion reflecting electric field back through the charge detection cylinder 440 towards the front mirror or end cap 436. Another delay time t follows the transition of the voltage (one or more) V5 to the ion transmitting state to release the ions from the ion trap 418. D2Upon expiration of the trapping time period t , the voltage V9 to the front ion mirror or end cap 436 is switched from a transmitting state to a trapping or reflecting state. Ions in the charge detection cylinder 440 or in the rear ion mirror or end cap 438 upon such switching of the voltage V9 to the trapping or reflecting state are thus trapped in the ELIT 434, and with both ion mirrors 436, 438 in their reflecting modes, the trapped ion(s) oscillate back and forth between the ion mirrors 436, 438, each time passing through the charge detection cylinder 440 and inducing a corresponding charge therein, as described above. The ion(s) are trapped for a period of time t , as shown in FIG. 11 . trap remains trapped in the ELIT 434 for a trapping time period t trap At the end of the sequence, voltages V9 and V10 return to their transmitting states to empty the ELIT 434 before beginning the sequence again. The resulting charge detection signals produced by the charge preamplifier 442 in response to detecting the charge induced in the charge detection cylinder by the ions passing through the charge detection cylinder are processed by the processor 444 to determine the mass and charge of the trapped ion(s), as described above. In some embodiments, the voltages are controlled as described herein to trap one ion in the ELIT 434, and in other embodiments the voltages can be controlled to trap more than one ion in the ELIT 434.

[0106]

[0125] Pulsed mode operation of the CDMS device 400 provides improved detection efficiency by accumulating and storing ions in the ion trap 418 and then controllably releasing ions from the trap 418 such that their arrival at the ELIT 434 is synchronized with the opening and closing of the ion mirrors 436, 438 (transmission and reflection modes, respectively).

[0107]

[0126] As illustrated in FIG. 10, there is a substantial distance D1 (e.g., 0.86 m) between the ion exit of the ion trap 418 and the front end of the charge detection cylinder 440. In one embodiment, D1 is approximately 0.86 meters, but in alternative embodiments, D1 can be greater or less than 0.86 meters. In either case, the time it takes an ion to travel D1 depends on its kinetic energy and its mass-to-charge ratio (m / z). Since the energy analyzer 432 transmits only ions within a narrow kinetic energy distribution, the time of this passage or travel depends primarily on the m / z of the ion. If the pulse width period tw is short, a range of m / z values ​​can be measured in about 100 s for a given total delay time t D1 is trapped during t D is the time between the transition of the voltage(s) V5 to an ion transmission mode, corresponding to opening the ion ejection port of the ion trap 418 to release or eject ions therefrom, i.e., the fall of V5 at tw, and the transition of the voltage V9 to an ion trapping or reflection state, corresponding to closing the ion mirror 436 of the ELIT 434, i.e., the rise of V9 following the subsequent rise of V5 at tw, corresponding to the trapping of ion(s) in the ELIT 434. D =t D1 +t D2 The maximum mass-to-charge ratio m / z that can be trapped MAX The fastest (i.e. slowest) ions, under these circumstances, are those that have just entered the detection cylinder when the front end cap switches to reflecting mode.

[0108]

[0127] m / z MAX = 2eE[t D 2 / d1 2 ] (1)

[0109]

[0128] In Equation 1, the elementary charge E is the ion energy, and d1 is as described above and shown in Figure 10. The minimum mass-to-charge ratio m / z that can be trapped is MINThe fastest (i.e., fastest) ions are those traveling through the charge detection cylinder 440 when voltage V9 switches to the reflective state, are reflected by the rear ion mirror or end cap 438, travel back through the charge detection cylinder 440, and are about to exit through the front ion mirror or end cap 436.

[0110]

[0129] m / z MIN = 2eE[t D 2 / (d1+ 2d2+ d3) 2 ] (2)

[0111]

[0130] In equation 2, d2 is the length of the charge detection cylinder 440, and d3 is the distance between the inlet / outlet of each ion mirror 436, 438 and the corresponding end of the charge detection cylinder 440. The 2d2 in equation (2) is so because ions travel both forward and backward through the charge detection cylinder 440, and d3 is determined from the time spent in the end caps. In some embodiments of the ELIT 434, d2=d3, and therefore the time spent by an ion traveling through the charge detection cylinder 440 is equal to the time spent traveling through each end cap 436, 438. In such embodiments, equation (2) can be reduced to:

[0112]

[0131] m / z MIN = 2eE[t D 2 / (d1+ 3d2) 2 ] (3)

[0113]

[0132] Therefore, the ratio of the maximum and minimum m / z that can be trapped is given by the following formula:

[0114]

[0133] m / z MAX / m / z MIN = (d1+ 3d2) 2 / d1 2 (4)

[0115]

[0134] Therefore, the range of m / z values ​​that can be trapped depends on the ion energy and the delay time t D For longer delay times, the m / z window shifts to larger m / z values, but the relative width of the m / z window remains the same. As noted above, the ratio of maximum to minimum m / z values ​​for the CDMS instrument 400 with d2 = d3 is 1.38, so for one delay time t D The width of the m / z window that can be trapped using MIN to 1.38 × m / z MIN For example, the delay time t is set so that the minimum m / z value that can be trapped is 25 kDa. D When set, ions with m / z values ​​up to 34.5 kDa can be trapped simultaneously.

[0116]

[0135] example

[0117]

[0136] Truncated Hepatitis B virus (HBV) capsid protein (Cp149) was assembled in 300 mM sodium chloride for 24 h, dialyzed into 100 mM ammonium acetate (Sigma Aldrich, 99.999% trace metal basis), and stored for at least 1 week before use (to allow assembly errors time to self-correct). The initial concentration of capsid protein was 1 mg / mL. Assembly yielded primarily icosahedral T=4 capsids (diameter approximately 32 nm) composed of 120 capsid protein dimers, along with a small amount (in this case approximately 5%) of icosahedral T=3 capsids with 90 protein dimers. The pseudo critical concentration for HBV assembly in 300 mM NaCl is 3.7 μM, therefore the final capsid concentration is approximately 0.22 μM. Stock samples were purified by size exclusion chromatography (SEC) with a 6 kDa cutoff. Aliquots of the purified liquid were then diluted with 100 mM ammonium acetate to the required concentrations, ranging from 0.05 μg / mL to 100 μg / mL.

[0118]

[0137] Pyruvate kinase (PK) was prepared at 10 mg / mL in ammonium acetate. An aliquot of the stock solution was purified by SEC with a 6 kDa cutoff. The purified liquid was then diluted to 2 mg / mL with 100 mM ammonium acetate.

[0119]

[0138] FIG. 12A shows several portions of two representative mass distributions of HBV samples measured using the CDMS device 400 illustrated in FIG. 10 and described above. Results are shown for two concentrations: 100 μg / mL (a 100-fold dilution of the HBV stock solution), shown as 500 in FIG. 12A, and 0.5 μg / mL (a 2000-fold dilution), shown as 502 in FIG. 12A. The CDMS distribution shown in FIG. 12A was recorded for 16.6 minutes (10,000 trapping events) and plotted in 25 kDa bins. At a concentration of 10 μg / mL (represented as 500), there is a prominent peak at a mass of approximately 4.05 MDa, which is close to the expected mass for the HBV Cp149 T=4 capsid. At a concentration of 0.5 μg / mL (represented as 502), the peak has almost disappeared. Note that the rate of spurious signals in CDMS is very small because the ions are measured for a relatively long time (100 ms). The HBV T=4 capsid ion has an elementary charge of about 140 electrons, and the chance that a random noise signal could be camouflaged as an ion signal of this magnitude over a 100 ms time period is quite small. Thus, the background noise in the range of interest is quite small as well.

[0120]

[0139] It should be noted that the number of analytes contained in the electrospray droplets may affect the detection efficiency. An estimate of the average number of capsids present in the droplets can be obtained, for example, from the concentration and droplet size. Also, the average size of the main electrospray droplets can be estimated from the electrospray conditions. If the estimated droplet size is 70 nm, the average number of capsids per droplet is about 0.025 (i.e., 1 in 40 droplets contains a capsid) at the concentration of HBV stock solution (1 mg / mL).

[0121]

[0140] FIG. 12B shows a log-log plot 504 of integrated counts ranging from 3.8 MDa to 4.4 MDa for HBV concentrations from 0.5 μg / mL to 10 μg / mL. The points are measurements and the lines are illustrative least squares fits. A slope of 1.0 is expected for a log-log plot of response versus concentration, and slopes close to 1.0 have been observed. In plot 504 of FIG. 12B, for example, the slope is 1.031. Based on these results, the limit of detection for HBV T=4 capsids can be approximately 0.5 μg / mL. This is in line with a 1.1×10 -10 mol / L or 6.6 x 10 10 corresponds to 1.3 μL of particles / mL. During the 16.6 minute collection period, approximately 1.3 μL of liquid was electrosprayed. Taking this into account, the limit of detection is therefore approximately 0.14 femtomoles or 8.6×10 7 During a data acquisition time of 16.6 min, 19 ions were detected. Thus, the detection efficiency for the HBV T=4 capsid was approximately 2.2 × 10 -7 It is.

[0122]

[0141] 13A shows a comparison of mass distributions measured by CDMS instrument 400 in both standard (i.e., non-pulsed) mode (designated 602 in FIG. 13A) and the pulsed mode described herein (designated 600 in FIG. 13A) for HBV capsid at a concentration of 1 μg / mL. Clearly, the intensity in distribution 600 measured in pulsed mode is significantly greater than the intensity in distribution 602 measured in standard (non-pulsed) mode, with the standard mode distribution containing 15 ions and the pulsed mode containing 3695, thus the gain in intensity in this example is 246.

[0123]

[0142] 13B shows another comparison of mass distributions between standard (non-pulsed) mode 606 and pulsed mode 604. In this case, the standard mode distribution 606 was measured at a concentration of 0.5 μg / mL and the pulsed mode distribution 604 was measured at a concentration of 0.05 μg / mL. The standard mode distribution 606 contains 8 ions and the pulsed mode distribution 604 contains 145, therefore the intensity gain is 181 (accounting for the concentration difference).

[0124]

[0143] The intensity gain depends on the trapping efficiency, the pulse width period tw, and the delay time t D1 and t D2 (all shown in FIG. 11). It was found that the signal from ions trapped in the ion trap 418 persists for more than 20 seconds after the electrospray source 404 is turned off, indicating that the ions are efficiently trapped in the ion trap 418. If the pulse width tw is too short, there is not enough time for the ions to leave the ion trap 418. On the other hand, if the pulse width tw is too long, the benefit of accumulating ions in the ion trap 418 is lost and the signal approaches the value for the non-pulsed mode. The pulse width tw and delay time t D1 and t D2 Once optimized, the intensity gain from pulsed mode operation was found to average about 200. It should be noted that for an m / z of 2800 Da, only about 1 ion out of 620 can be trapped in the non-pulsed mode of operation of the CDMS instrument 400. By operating in pulsed mode as described above, a large portion of the signal that is lost in non-pulsed mode can be recovered. With the pulsed mode of operation exemplified and described here, the limit of detection for the HBV T=4 capsid is about 200 times lower, at 5.5×10 -13 mol / L or 3.3 x 10 8 particles / mL, which is approximately 4.3 x 10 for a 1.3 μL sample. 5 The detection efficiency for HBV T=4 capsids in pulsed mode of operation is approximately 4.4 x 10 particles or approximately 0.7 attomoles. -5(i.e. 200 times the detection efficiency in non-pulsed mode).

[0125]

[0144] Given the high sensitivity afforded by CDMS in pulsed mode, it is relatively easy to inject many ions simultaneously into the ELIT. However, although multiple ion trapping events can be analyzed to determine the m / z values ​​and charges of a small number of simultaneously trapped ions, ion-ion interactions in the ELIT434 can fluctuate trajectories and energies, which degrades m / z resolution. Trapping of multiple ions with similar m / z values ​​can introduce errors in the data analysis, and the measurements depicted in the attached figures are limited to samples where, on average, one ion is trapped per trapping event. The distribution of trapped ions is Poissonian, and for an average trapping efficiency of about 1, roughly one third of the trapping events are empty, another third contain one ion, and the remaining third contain two or more ions. For a sample concentration of 10 μg / mL, the number of ions trapped in pulsed mode is on average significantly more than one per event, and the sample must be diluted to allow the measurements depicted in the attached figures to be made.

[0126]

[0145] As discussed above, assembly of HBV capsid proteins results in a small amount of small T=3 capsids in addition to T=4. The mean m / z of the T=4 ions is 28700 Da and the mean m / z of the T=3 ions is 25500 Da. The ratio of these m / z values ​​is 1.13, which is within the range of simultaneous trapping. In this regard, FIG. 14 shows CDMS mass distributions 700, 702 for HBV measured using CDMS instrument 400, showing a T=3 peak at about 3.0 MDa and a T=4 peak at about 4.05 MDa. Distribution 702 was measured using CDMS instrument 400 under standard operating conditions (i.e., non-pulsed) and distribution 700 was measured using CDMS instrument 400 operated in pulsed mode as described above. The concentration of HBV proteins was 100 μg / mL for the non-pulsed form (distribution 702) and 1 μg / mL for the pulsed form (distribution 700). The fraction of capsids at T=3 (from integrated counts) is 0.0435 for distribution 702 in standard mode and 0.0470 for distribution 700 in pulsed mode. However, the detection efficiency for distribution 702 in standard mode is (m / z) 0.0470 because larger (i.e., slower) ions spend more time in the trappable region of the ELIT434. 1 / 2 In pulsed mode operation of the CDMS instrument 400, all ions in the trapping volume of the ELIT 434 are trapped, and the detection efficiency for these ions is independent of the m / z ratio. After correction of the standard mode ratio for detection efficiency, the ratio increases to 0.0461 (compared to 0.0470 for pulsed mode). Thus, the intensity ratio is not significantly affected by pulsed mode operation.

[0127]

[0146] The m / z distribution is MIN to 1.38 × m / z MIN If the window is wider than t Dcan be adjusted to trap different parts of the distribution. For example, FIG. 15 shows the CDMS mass distribution for a pyruvate kinase (PK) sample measured using the CDMS device 400. The mass distribution 804 was measured under standard (i.e., non-pulsed) conditions and clearly shows peaks due to PK tetramers (230 kDa), octamers (460 kDa), dodecamers (690 kDa), and hexadecamers (920 kDa). It is not possible to simultaneously transmit all multimers in pulsed mode. However, the delay time t D It is possible to transmit different m / z bands by adjusting the delay time t . The mass distribution 800 has a delay time t optimized to transmit m / z values ​​including quartets (m / z values ​​in the range of about 6600 Da to 9150 Da are transmitted). D The mass distribution 802 is measured in pulse mode with a delay time t optimized to transmit octamer and decamer. D The measurements were performed in pulsed mode using a 1000 Hz pulsed NMR spectrometer. In both cases the ratio of the minimum and maximum mass-to-charge ratio transmitted is close to the predicted value (1.38) above. The ability to select some portion of the m / z distribution is beneficial in many applications. For example, since individual ions are processed in CDMS, it is beneficial to not waste time processing ions that do not contain useful information. Thus, as mentioned above, differentiation of portions of the m / z distribution that do not contain useful information is beneficial. Many samples contain many low mass ions that can be differentiated using this approach.

[0128]

[0147] In the exemplary embodiment of the apparatus 400 described herein, the ion mass and charge detector 434 is provided in the form of a single stage electrostatic linear ion trap (ELIT), although it will be appreciated that in other embodiments the ion mass and charge detector 434 may alternatively be provided in the form of a multi-stage ELIT, such as the ELIT 14 described herein with reference to Figures 1-4E, or a plurality of single stage ELITs, such as those described herein with reference to Figures 6-8F, or in some embodiments one or more orbitraps, such as those disclosed in co-pending International Patent Application No. PCT / US2019 / 013278 below. In the first two cases, the operation of the apparatus 400 may be modified without contradicting the description of the systems 10, 200 above to sequentially feed ions to the multi-stage ELIT or stages of ELITs. 1-4E and described above, each ELIT region (e.g., E1, E2, and E3) is spaced at progressively larger distances from the ion trap 418, and each has somewhat different minimum and maximum mass-to-charge ratio values. Note further that the range of mass-to-charge ratios that can be trapped in each of the ELIT regions, as given by equation (4) above, progressively decreases in value as the distance of the ELIT region from the ion trap 418 increases.

[0129]

[0148] The dimensions of the various components of any of the ELITs and / or arrays 14, 205, 302, 434 illustrated in the accompanying drawings and described above can be selected, by way of example, to establish a desired duty cycle of ion oscillation therein and / or in each ELIT or ELIT region E1-E3, which corresponds to the ratio of the time consumed by an ion(s) in an individual charge detection cylinder(s) CD1-CD3 to the total time consumed by an ion(s) traversing the corresponding ion mirror and individual charge detection cylinder(s) CD1-CD3 combination during one complete oscillation cycle. For example, a duty cycle of about 50% can be desirable in the ELIT or one or more of the ELIT regions for the purpose of reducing noise in the determination of the fundamental frequency magnitude resulting from harmonic frequency components of the measurement signal. Such dimensional considerations and related details for achieving a desired duty cycle, such as 50%, are exemplified and described in co-pending International Patent Application No. PCT / US2019 / 013251, filed January 11, 2019, and entitled "ELECTROSTATIC LINEAR ION TRAP DESIGN FOR CHARGE DETECTION MASS SPECTROSCOPY," the disclosure of which is expressly incorporated herein by this reference in its entirety.

[0130]

[0149] It will further be understood that a charge calibration or resetting apparatus can be used with the charge detection cylinder(s) of any one or more of the ELITs and / or arrays 14, 205, 302, 434 and / or in any one or more of the regions E1-E3 of the ELITs or ELIT arrays. An example of one such charge calibration or resetting apparatus is illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013284, filed January 11, 2019, and International Patent Application No. PCT / US2019 / 035381, filed June 4, 2019, both of which are entitled "APPARATUS AND METHOD FOR CALIBRATING OR RESETTING A CHARGE DETECTOR," the disclosures of which are expressly incorporated herein by reference in their entireties.

[0131]

[0150] It will further be appreciated that one or more charge detection optimization techniques can be used in conjunction with any one or more of the ELITs and / or arrays 14, 205, 302, 434, and / or with one or more regions E1-E3 of such ELITs and / or ELIT arrays, to trigger trapping or other charge detection events. Examples of some such charge detection optimization apparatus and techniques are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013280, filed Jan. 11, 2019, and entitled “APPARATUS AND METHOD FOR CAPTURING IONS IN AN ELECTROSTATIC LINEAR ION TRAP,” the disclosure of which is expressly incorporated herein by this reference in its entirety.

[0132]

[0151] It will further be understood that one or more ion source optimization devices and / or techniques can be used in conjunction with one or more embodiments of the ion source 12 illustrated and described herein, some examples of which are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013274, filed January 11, 2019, and International Patent Application No. PCT / US2019 / 035379, filed June 4, 2019, both entitled “HYBRID ION FUNNEL-ION CARPET (FUNPET) ATMOSPHERIC PRESSURE INTERFACE FOR CHARGE DETECTION MASS SPECTROMETRY,” the disclosures of which are expressly incorporated herein by reference in their entireties.

[0133]

[0152] It will further be understood that the ion mass detection systems 10, 60, 80, 200, 300, 400 illustrated and described herein may be implemented in accordance with real-time analysis and / or real-time control techniques, some examples of which are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013277, filed January 11, 2019, and entitled "CHARGE DETECTION MASS SPECTROMETRY WITH REAL TIME ANALYSIS AND SIGNAL OPTIMIZATION," the disclosure of which is expressly incorporated herein by reference in its entirety.

[0134]

[0153] It will further be understood that the ion mass detection systems 10, 60, 80, 200, 300, 400 illustrated and described herein can be configured to provide multiple ions to any one or more of the ELITs and / or arrays 14, 205, 302, 434 illustrated and described herein such that one or more of such ELITs and / or ELIT arrays are operable to measure the mass and charge of multiple ions at once, some examples of which are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013285, filed on January 11, 2019, and entitled “APPARATUS AND METHOD FOR SIMULTANEOUSLY ANALYZING MULTIPLE IONS WITH AN ELECTROSTATIC LINEAR ION TRAP,” the disclosure of which is expressly incorporated herein by reference in its entirety.

[0135]

[0154] It is further understood that in one or more of the ion mass detection systems 10, 60, 80, 200, 300, 400 illustrated and described herein, at least one ELIT can alternatively be provided in the form of an orbitrap, some examples of which are illustrated and described in co-pending International Patent Application No. PCT / US2019 / 013278, filed January 11, 2019, and entitled "ORBITRAP FOR SINGLE PARTICLE MASS SPECTROMETRY," the disclosure of which is expressly incorporated herein by reference in its entirety.

[0136]

[0155] It will further be understood that the CDMS device 400 is included as an additional embodiment of the ion mass detection apparatus illustrated in Figure 5A and described above (i.e., as an alternative to the ion mass detection systems 10, 200, 300). Similarly, it will be understood that the CDMS device 400 is included as an additional embodiment of the ion mass detection apparatus illustrated in Figure 5B and described above (i.e., as an alternative to the ion mass detection systems 10, 200, 300).

[0137]

[0156] While the invention has been illustrated and described in detail in the drawings and description above, it is to be understood that the same is to be considered as illustrative and not limiting in character, and that only exemplary embodiments thereof have been shown and described, and that protection for all changes and modifications which come within the spirit of the invention is desired.

Claims

1. 1. A charge detection mass spectrometer, comprising: an ion source configured to generate ions from the sample; an ion trap configured to receive and store the generated ions and to release the stored ions through an ion outlet in the ion trap; an electrostatic linear ion trap (ELIT) spaced from the ion trap and including a first ion mirror and a second ion mirror and a charge detection cylinder disposed between the first ion mirror and the second ion mirror; at least one voltage source configured to produce a plurality of output voltages, the ion trap is coupled to a first set of multiple output voltages and configured to receive and store the ions generated in the ion trap in response to trapping states of the first set of multiple output voltages and configured to release stored ions from the ion outlet in the ion trap in response to transmission states of the first set of multiple output voltages; the first ion mirror and the second ion mirror in the ELIT are coupled to a second set of a plurality of output voltages and a third set of a plurality of output voltages, respectively, the first ion mirror and the second ion mirror are configured to transmit ions through the first ion mirror and the second ion mirror, respectively, in response to a transmission state of the second set of a plurality of output voltages and the third set of a plurality of output voltages, respectively, and are configured to reflect ions entering the first ion mirror and the second ion mirror, respectively, from the charge detection cylinder back into the charge detection cylinder in response to a reflection state of the second set of a plurality of output voltages and the third set of a plurality of output voltages, respectively; at least one voltage source; a processing circuit for controlling the first set of multiple output voltages, the second set of multiple output voltages, and the third set of multiple output voltages, configured to control the first set of output voltages from the trapping state to the transmission state during a pulse width period to release stored ions from the ion ejection port in the ion trap and move them through the first ion mirror and into the ELIT; configured to control the third set of output voltages from the trapping state to the reflecting state when a first delay time from controlling the first set of output voltages from the trapping state to the transmitting state expires, and thereafter to control the second set of output voltages from the transmitting state to the reflecting state when a second delay time from controlling the first set of output voltages from the trapping state to the transmitting state expires, to trap at least one of the ions moving from the ion trap toward the ELIT in the ELIT, and to oscillate the trapped at least one ion back and forth between the first ion mirror and the second ion mirror, each time passing through the charge detection cylinder and inducing a corresponding charge into the charge detection cylinder; a minimum and a maximum mass-to-charge ratio of the at least one ion trapped in the ELIT are proportional to a sum of the first delay time and the second delay time, and the sum of the first delay time and the second delay time is controlled by the processing circuitry to select a corresponding mass-to-charge ratio range for ions to be trapped in the ELIT. A processing circuit; 1. A charge detection mass spectrometer comprising:

2. 10. The charge detection mass spectrometer of claim 1, further comprising: a charge sensitive preamplifier having an input coupled to the charge detection cylinder and an output, the charge sensitive preamplifier responsive to detecting a charge induced in the charge detection cylinder by the at least one trapped ion passing through the charge detection cylinder to produce a corresponding charge detection signal at the output of the charge sensitive preamplifier; means for processing a plurality of said charge detection signals to determine the mass and charge of said at least one trapped ion; 1. A charge detection mass spectrometer comprising:

3. 10. The charge detection mass spectrometer of claim 1, further comprising: a mass to charge ratio filter disposed between the ion trap and the ELIT, the mass to charge ratio filter being configured to allow only ions having a mass to charge ratio above a mass to charge ratio threshold, below a mass to charge ratio threshold, or within a selected mass to charge ratio range, to pass through the mass to charge ratio filter.

4. 3. The charge detection mass spectrometer of claim 2, A charge detection mass spectrometer, wherein the processing circuitry is configured to process the plurality of charge detection signals to determine the mass and the charge of the at least one trapped ion.

5. 2. The charge detection mass spectrometer of claim 1, 11. A charge detection mass spectrometer, wherein the processing circuitry is configured to control the first set of multiple output voltages from the transmission state to the trapping state in response to expiration of the pulse width period.

6. 2. The charge detection mass spectrometer of claim 1, a first ion mirror facing the ion trap, the ion ejection port of the ion trap being spaced a first distance from a first end of the charge detection cylinder facing the first ion mirror, a length of the charge detection cylinder between the first end of the charge detection cylinder and a second end of the charge detection cylinder facing the second ion mirror defining a second distance, the first distance and the second distance defining a range of mass-to-charge ratio values ​​of ions that can be trapped in the ELIT.

7. 7. The charge detection mass spectrometer of claim 6, further comprising: a charge sensitive preamplifier having an input coupled to the charge detection cylinder and an output, the charge sensitive preamplifier producing a charge detection signal at the output of the charge sensitive preamplifier in response to detecting charge induced in the charge detection cylinder by the at least one ion passing through the charge detection cylinder; A charge detection mass spectrometer, wherein the processing circuitry is configured to process a plurality of the charge detection signals to determine the mass and charge of the at least one trapped ion.

8. 7. The charge detection mass spectrometer of claim 6, further comprising: a mass-to-charge ratio filter disposed between the ion trap and the ELIT; 1. A charge detection mass spectrometer, wherein the mass to charge ratio filter is configured such that only ions having a mass to charge ratio above a mass to charge ratio threshold, below a mass to charge ratio threshold, or within a selected mass to charge ratio range, pass through the mass to charge ratio filter.

9. 1. A method of operating a charge detection mass spectrometer including an ion trap and an electrostatic linear ion trap (ELIT) having a charge detection cylinder disposed between a front ion mirror and a rear ion mirror, an ion ejection port in the ion trap being axially spaced a first distance from an end of the charge detection cylinder facing the front ion mirror of the ELIT, the charge detection cylinder defining a second distance between opposing ends of the charge detection cylinder, the first and second distances establishing a range of mass-to-charge ratio values ​​for ions trappable in the ELIT, the method comprising: generating ions from a sample; storing the generated ions in the ion trap; controlling the ion trap to release at least some of the stored ions from the ion ejection port in the ion trap and move them through the front ion mirror and into the ELIT; a first delay time after controlling the ion trap to release stored ions from the ion ejection port in the ion trap, controlling the rear ion mirror to a reflective state such that the rear ion mirror reflects ions entering the rear ion mirror from the charge detection cylinder back through the charge detection cylinder towards the front ion mirror; controlling the front ion mirror to a reflective state after a second delay time after controlling to release the stored ions from the ion ejection port of the ion trap, so that the front ion mirror reflects ions entering the front ion mirror from the charge detection cylinder back through the charge detection cylinder towards the rear ion mirror, trapping at least one of the ions released from the ion ejection port of the ion trap with the ELIT, such that the at least one trapped ion oscillates back and forth between the front ion mirror and the rear ion mirror, passing through the charge detection cylinder each time and inducing a corresponding charge into the charge detection cylinder; the second delay time is greater than the first delay time, and a minimum and a maximum mass-to-charge ratio of the at least one trapped ion are proportional to the sum of the first delay time and the second delay time; A method comprising:

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